diff --git a/include/eepp/core/memorymanager.hpp b/include/eepp/core/memorymanager.hpp
index 4d716f39e..cd137d257 100644
--- a/include/eepp/core/memorymanager.hpp
+++ b/include/eepp/core/memorymanager.hpp
@@ -12,10 +12,12 @@ namespace EE {
 
 class EE_API AllocatedPointer {
   public:
-	AllocatedPointer( void* data, const std::string& File, int Line, size_t memory,
-					  bool track = false, bool globalAllocation = false );
+	/** file must have static storage duration. All memory-manager entry points pass __FILE__ or a
+	 * string literal, so retaining the pointer avoids allocating bookkeeping strings. */
+	AllocatedPointer( void* data, const char* file, int line, size_t memory, bool track = false,
+					  bool globalAllocation = false );
 
-	std::string mFile;
+	const char* mFile;
 	int mLine;
 	size_t mMemory;
 	void* mData;
diff --git a/include/eepp/core/small_function.hpp b/include/eepp/core/small_function.hpp
new file mode 100644
index 000000000..24f011995
--- /dev/null
+++ b/include/eepp/core/small_function.hpp
@@ -0,0 +1,174 @@
+#ifndef EE_CORE_SMALL_FUNCTION_HPP
+#define EE_CORE_SMALL_FUNCTION_HPP
+
+#include <cstddef>
+#include <functional>
+#include <new>
+#include <type_traits>
+#include <utility>
+
+namespace EE {
+
+/** Copyable type-erased void callable with inline storage and a heap fallback.
+ *
+ * This intentionally implements only the signature used by the scene scheduler. Ordinary lambdas
+ * stay inside the object; unusually large or over-aligned callables retain std::function-like
+ * fallback behavior.
+ */
+template <std::size_t InlineSize = 64> class SmallFunction {
+  public:
+	SmallFunction() noexcept = default;
+	SmallFunction( std::nullptr_t ) noexcept {}
+
+	SmallFunction( const SmallFunction& other ) {
+		if ( other.mVTable )
+			other.mVTable->copy( *this, other );
+	}
+
+	SmallFunction( SmallFunction&& other ) {
+		if ( other.mVTable )
+			other.mVTable->move( *this, other );
+	}
+
+	template <typename Callable, typename Decayed = std::decay_t<Callable>,
+			  std::enable_if_t<!std::is_same_v<Decayed, SmallFunction> &&
+								   std::is_invocable_r_v<void, Decayed&>,
+							   int> = 0>
+	SmallFunction( Callable&& callable ) {
+		emplace<Decayed>( std::forward<Callable>( callable ) );
+	}
+
+	~SmallFunction() { reset(); }
+
+	SmallFunction& operator=( const SmallFunction& other ) {
+		if ( this != &other ) {
+			reset();
+			if ( other.mVTable )
+				other.mVTable->copy( *this, other );
+		}
+		return *this;
+	}
+
+	SmallFunction& operator=( SmallFunction&& other ) {
+		if ( this != &other ) {
+			reset();
+			if ( other.mVTable )
+				other.mVTable->move( *this, other );
+		}
+		return *this;
+	}
+
+	template <typename Callable, typename Decayed = std::decay_t<Callable>,
+			  std::enable_if_t<!std::is_same_v<Decayed, SmallFunction> &&
+								   std::is_invocable_r_v<void, Decayed&>,
+							   int> = 0>
+	SmallFunction& operator=( Callable&& callable ) {
+		reset();
+		emplace<Decayed>( std::forward<Callable>( callable ) );
+		return *this;
+	}
+
+	SmallFunction& operator=( std::nullptr_t ) noexcept {
+		reset();
+		return *this;
+	}
+
+	explicit operator bool() const noexcept { return nullptr != mVTable; }
+
+	void operator()() const {
+		if ( !mVTable )
+			throw std::bad_function_call();
+		mVTable->invoke( const_cast<SmallFunction&>( *this ) );
+	}
+
+	void reset() noexcept {
+		if ( mVTable ) {
+			mVTable->destroy( *this );
+			mVTable = nullptr;
+		}
+	}
+
+	static constexpr std::size_t inlineSize() noexcept { return InlineSize; }
+
+  private:
+	static constexpr std::size_t StorageSize =
+		InlineSize < sizeof( void* ) ? sizeof( void* ) : InlineSize;
+	using Storage = std::aligned_storage_t<StorageSize, alignof( std::max_align_t )>;
+
+	struct VTable {
+		void ( *invoke )( SmallFunction& );
+		void ( *copy )( SmallFunction&, const SmallFunction& );
+		void ( *move )( SmallFunction&, SmallFunction& );
+		void ( *destroy )( SmallFunction& ) noexcept;
+	};
+
+	template <typename Callable>
+	static constexpr bool FitsInline =
+		sizeof( Callable ) <= StorageSize && alignof( Callable ) <= alignof( Storage );
+
+	template <typename Callable> static Callable*& heapPointer( SmallFunction& function ) {
+		return *reinterpret_cast<Callable**>( &function.mStorage );
+	}
+
+	template <typename Callable> static Callable* inlinePointer( SmallFunction& function ) {
+		return reinterpret_cast<Callable*>( &function.mStorage );
+	}
+
+	template <typename Callable, typename Value> void emplace( Value&& value ) {
+		static_assert( std::is_copy_constructible_v<Callable>,
+					   "SmallFunction requires a copy-constructible callable" );
+		if constexpr ( FitsInline<Callable> ) {
+			new ( &mStorage ) Callable( std::forward<Value>( value ) );
+			mVTable = &inlineVTable<Callable>();
+		} else {
+			heapPointer<Callable>( *this ) = new Callable( std::forward<Value>( value ) );
+			mVTable = &heapVTable<Callable>();
+		}
+	}
+
+	template <typename Callable> static const VTable& inlineVTable() {
+		static const VTable table{
+			[]( SmallFunction& function ) { ( *inlinePointer<Callable>( function ) )(); },
+			[]( SmallFunction& destination, const SmallFunction& source ) {
+				new ( &destination.mStorage )
+					Callable( *inlinePointer<Callable>( const_cast<SmallFunction&>( source ) ) );
+				destination.mVTable = &inlineVTable<Callable>();
+			},
+			[]( SmallFunction& destination, SmallFunction& source ) {
+				new ( &destination.mStorage )
+					Callable( std::move( *inlinePointer<Callable>( source ) ) );
+				inlinePointer<Callable>( source )->~Callable();
+				destination.mVTable = &inlineVTable<Callable>();
+				source.mVTable = nullptr;
+			},
+			[]( SmallFunction& function ) noexcept {
+				inlinePointer<Callable>( function )->~Callable();
+			} };
+		return table;
+	}
+
+	template <typename Callable> static const VTable& heapVTable() {
+		static const VTable table{
+			[]( SmallFunction& function ) { ( *heapPointer<Callable>( function ) )(); },
+			[]( SmallFunction& destination, const SmallFunction& source ) {
+				heapPointer<Callable>( destination ) =
+					new Callable( *heapPointer<Callable>( const_cast<SmallFunction&>( source ) ) );
+				destination.mVTable = &heapVTable<Callable>();
+			},
+			[]( SmallFunction& destination, SmallFunction& source ) {
+				heapPointer<Callable>( destination ) = heapPointer<Callable>( source );
+				heapPointer<Callable>( source ) = nullptr;
+				destination.mVTable = &heapVTable<Callable>();
+				source.mVTable = nullptr;
+			},
+			[]( SmallFunction& function ) noexcept { delete heapPointer<Callable>( function ); } };
+		return table;
+	}
+
+	Storage mStorage;
+	const VTable* mVTable{ nullptr };
+};
+
+} // namespace EE
+
+#endif
diff --git a/include/eepp/math/ease.hpp b/include/eepp/math/ease.hpp
index 2371aeca7..36d52eda4 100644
--- a/include/eepp/math/ease.hpp
+++ b/include/eepp/math/ease.hpp
@@ -1,8 +1,8 @@
 #ifndef EE_MATH_EASE
 #define EE_MATH_EASE
 
-#include <eepp/system/functionstring.hpp>
 #include <string>
+#include <string_view>
 
 namespace EE { namespace Math {
 
@@ -118,7 +118,7 @@ class Ease {
 		return "";
 	}
 
-	static Interpolation fromName( const std::string& name,
+	static Interpolation fromName( std::string_view name,
 								   const Interpolation& defaultInterpolation = Ease::Linear ) {
 		if ( "linear" == name )
 			return Ease::Linear;
@@ -184,13 +184,22 @@ class Ease {
 			return Ease::ElasticInOut;
 		if ( "cubicbezier" == name || "cubic-bezier" == name )
 			return Ease::CubizBezier;
-		// Handle the case that the name is a function
-		if ( name.find_first_of( '(' ) != std::string::npos ) {
-			System::FunctionString func( System::FunctionString::parse( name ) );
-			return fromName( func.getName(), defaultInterpolation );
-		}
+		// Function parameters do not participate in interpolation-name lookup.
+		const auto functionStart = name.find_first_of( '(' );
+		if ( functionStart != std::string_view::npos )
+			return fromName( name.substr( 0, functionStart ), defaultInterpolation );
 		return defaultInterpolation;
 	}
+
+	static Interpolation fromName( const std::string& name,
+								   const Interpolation& defaultInterpolation = Ease::Linear ) {
+		return fromName( std::string_view{ name }, defaultInterpolation );
+	}
+
+	static Interpolation fromName( const char* name,
+								   const Interpolation& defaultInterpolation = Ease::Linear ) {
+		return fromName( std::string_view{ name }, defaultInterpolation );
+	}
 };
 
 }} // namespace EE::Math
diff --git a/include/eepp/scene/action.hpp b/include/eepp/scene/action.hpp
index 357e18c95..6d4b53b57 100644
--- a/include/eepp/scene/action.hpp
+++ b/include/eepp/scene/action.hpp
@@ -1,6 +1,7 @@
 #ifndef EE_SCENEACTION_HPP
 #define EE_SCENEACTION_HPP
 
+#include <cstddef>
 #include <eepp/core.hpp>
 #include <eepp/system/time.hpp>
 using namespace EE::System;
@@ -21,6 +22,18 @@ class EE_API Action {
 
 	virtual ~Action();
 
+	/** Allocates actions from a shared size-class pool. Existing Action factories and ownership
+	 * semantics are unchanged; completed slots are recycled by operator delete. */
+	static void* operator new( std::size_t size );
+
+	static void operator delete( void* ptr ) noexcept;
+
+	static void operator delete( void* ptr, std::size_t size ) noexcept;
+
+	static void* operator new( std::size_t, void* place ) noexcept { return place; }
+
+	static void operator delete( void*, void* ) noexcept {}
+
 	/** Starts the action. */
 	virtual void start() = 0;
 
@@ -91,7 +104,12 @@ class EE_API Action {
 
   protected:
 	friend class Node;
-	typedef UnorderedMap<ActionType, UnorderedMap<Uint32, ActionCallback>> ActionCallbackMap;
+	struct ActionCallbackEntry {
+		ActionType type;
+		Uint32 id;
+		ActionCallback callback;
+	};
+	using ActionCallbackMap = SmallVector<ActionCallbackEntry, 2>;
 
 	Node* mNode{ nullptr };
 	Action::UniqueID mId{ 0 };
diff --git a/include/eepp/scene/actionmanager.hpp b/include/eepp/scene/actionmanager.hpp
index 72db7f21e..ade3a0d54 100644
--- a/include/eepp/scene/actionmanager.hpp
+++ b/include/eepp/scene/actionmanager.hpp
@@ -43,6 +43,9 @@ class EE_API ActionManager {
 
 	std::vector<Action*> getActionsByTagFromTarget( Node* target, const Action::UniqueID& tag );
 
+	void getActionsByTagFromTarget( Node* target, const Action::UniqueID& tag,
+									SmallVector<Action*, 4>& actions );
+
 	void update( const Time& time );
 
 	std::size_t count() const;
diff --git a/include/eepp/scene/actions/runnable.hpp b/include/eepp/scene/actions/runnable.hpp
index d17e3c4b6..f5d3f6376 100644
--- a/include/eepp/scene/actions/runnable.hpp
+++ b/include/eepp/scene/actions/runnable.hpp
@@ -1,15 +1,15 @@
 #ifndef EE_SCENE_ACTION_CALLBACK_HPP
 #define EE_SCENE_ACTION_CALLBACK_HPP
 
+#include <eepp/core/small_function.hpp>
 #include <eepp/scene/actions/delay.hpp>
 #include <eepp/system/mutex.hpp>
-#include <functional>
 
 namespace EE { namespace Scene { namespace Actions {
 
 class EE_API Runnable : public Delay {
   public:
-	typedef std::function<void()> RunnableFunc;
+	using RunnableFunc = SmallFunction<48>;
 
 	static Runnable* New( RunnableFunc callback, const Time& time = Seconds( 0 ),
 						  bool loop = false );
diff --git a/include/eepp/scene/actions/sequence.hpp b/include/eepp/scene/actions/sequence.hpp
index dcb17bc6f..2bd80e1b7 100644
--- a/include/eepp/scene/actions/sequence.hpp
+++ b/include/eepp/scene/actions/sequence.hpp
@@ -42,11 +42,14 @@ class EE_API Sequence : public Action {
 	virtual ~Sequence();
 
   protected:
-	std::vector<Action*> mSequence;
+	using ActionContainer = SmallVector<Action*, 4>;
+	ActionContainer mSequence;
 	Time mDuration;
 	Uint32 mCurPos;
 
 	Sequence( const std::vector<Action*> sequence );
+
+	Sequence( ActionContainer sequence );
 };
 
 }}} // namespace EE::Scene::Actions
diff --git a/include/eepp/scene/actions/spawn.hpp b/include/eepp/scene/actions/spawn.hpp
index 8f3bb992a..70073d954 100644
--- a/include/eepp/scene/actions/spawn.hpp
+++ b/include/eepp/scene/actions/spawn.hpp
@@ -42,10 +42,13 @@ class EE_API Spawn : public Action {
 	virtual ~Spawn();
 
   protected:
-	std::vector<Action*> mSpawn;
+	using ActionContainer = SmallVector<Action*, 4>;
+	ActionContainer mSpawn;
 	bool mAllDone;
 
 	Spawn( const std::vector<Action*> spawn );
+
+	Spawn( ActionContainer spawn );
 };
 
 }}} // namespace EE::Scene::Actions
diff --git a/include/eepp/scene/node.hpp b/include/eepp/scene/node.hpp
index 03488f2fb..64d85fb3b 100644
--- a/include/eepp/scene/node.hpp
+++ b/include/eepp/scene/node.hpp
@@ -1346,6 +1346,9 @@ class EE_API Node : public Transformable {
 	 */
 	std::vector<Action*> getActionsByTag( const Action::UniqueID& tag );
 
+	/** Appends matching actions to inline-capable storage without allocating in the common case. */
+	void getActionsByTag( const Action::UniqueID& tag, SmallVector<Action*, 4>& actions );
+
 	/**
 	 * @brief Removes all actions from this node.
 	 *
diff --git a/include/eepp/system/functionstring.hpp b/include/eepp/system/functionstring.hpp
index b789a758f..0d865c637 100644
--- a/include/eepp/system/functionstring.hpp
+++ b/include/eepp/system/functionstring.hpp
@@ -6,6 +6,7 @@
 #include <eepp/core/string.hpp>
 
 #include <string>
+#include <utility>
 
 namespace EE { namespace System {
 
@@ -14,6 +15,82 @@ class EE_API FunctionString {
 	using Parameters = SmallVector<std::string, 4>;
 	using TypeStringVector = SmallVector<bool, 4>;
 
+	class View {
+	  public:
+		View() = default;
+
+		std::string_view getName() const { return mName; }
+
+		bool isEmpty() const { return mName.empty(); }
+
+		template <typename Callback> bool forEachParameter( Callback&& callback ) const {
+			return FunctionString::forEachParameter( mParameters,
+													 std::forward<Callback>( callback ) );
+		}
+
+	  private:
+		friend class FunctionString;
+
+		View( std::string_view name, std::string_view parameters ) :
+			mName( name ), mParameters( parameters ) {}
+
+		std::string_view mName;
+		std::string_view mParameters;
+	};
+
+	static View parseView( std::string_view function );
+
+	/** Iterates a comma-separated parameter list without allocating. Nested parentheses and
+	 * quoted strings protect commas. Quoted parameters are reported without their outer quotes;
+	 * escaped quotes remain escaped because the returned views reference the original input.
+	 * The callback receives (parameter, parameterWasString) and returns whether to continue. */
+	template <typename Callback>
+	static bool forEachParameter( std::string_view parameters, Callback&& callback ) {
+		std::size_t start = 0;
+		int parenthesisDepth = 0;
+		char quote = 0;
+		bool escaped = false;
+
+		auto emit = [&]( std::size_t end ) {
+			std::string_view parameter =
+				String::trim( parameters.substr( start, end - start ), " \t\n\r\f\v" );
+			bool wasString = parameter.size() >= 2 &&
+							 ( parameter.front() == '\'' || parameter.front() == '"' ) &&
+							 parameter.back() == parameter.front();
+			if ( wasString )
+				parameter = parameter.substr( 1, parameter.size() - 2 );
+			if ( parameter.empty() && !wasString )
+				return true;
+			return callback( parameter, wasString );
+		};
+
+		for ( std::size_t i = 0; i < parameters.size(); ++i ) {
+			const char character = parameters[i];
+			if ( quote ) {
+				if ( escaped ) {
+					escaped = false;
+				} else if ( character == '\\' ) {
+					escaped = true;
+				} else if ( character == quote ) {
+					quote = 0;
+				}
+				continue;
+			}
+			if ( character == '\'' || character == '"' ) {
+				quote = character;
+			} else if ( character == '(' ) {
+				++parenthesisDepth;
+			} else if ( character == ')' && parenthesisDepth > 0 ) {
+				--parenthesisDepth;
+			} else if ( character == ',' && parenthesisDepth == 0 ) {
+				if ( !emit( i ) )
+					return false;
+				start = i + 1;
+			}
+		}
+		return emit( parameters.size() );
+	}
+
 	static FunctionString parse( const std::string& function );
 
 	static FunctionString parse( std::string_view function );
@@ -41,7 +118,7 @@ class EE_API FunctionString {
 	Parameters parameters;
 	TypeStringVector typeStringData;
 
-	template <typename StringType> static FunctionString parse( StringType function );
+	static FunctionString parseOwned( std::string_view function );
 };
 
 }} // namespace EE::System
diff --git a/include/eepp/ui/css/animationdefinition.hpp b/include/eepp/ui/css/animationdefinition.hpp
index 7f91b296b..68aa745d3 100644
--- a/include/eepp/ui/css/animationdefinition.hpp
+++ b/include/eepp/ui/css/animationdefinition.hpp
@@ -4,6 +4,7 @@
 #include <eepp/math/ease.hpp>
 #include <eepp/system/time.hpp>
 #include <eepp/ui/css/stylesheetproperty.hpp>
+#include <eepp/ui/css/timingfunction.hpp>
 #include <vector>
 
 using namespace EE::Math;
@@ -56,8 +57,12 @@ class EE_API AnimationDefinition {
 
 	const Ease::Interpolation& getTimingFunction() const;
 
+	/** Kept for source compatibility. Internal animation code uses the inline view below so this
+	 * legacy vector is only materialized when an external caller requests it. */
 	const std::vector<double>& getTimingFunctionParameters() const;
 
+	const TimingFunction::Parameters& getTimingFunctionParametersInline() const;
+
 	const AnimationFillMode& getFillMode() const;
 
 	void setName( const std::string& value );
@@ -72,6 +77,8 @@ class EE_API AnimationDefinition {
 
 	void setTimingFunctionParameters( const std::vector<double>& timingFunctionParameters );
 
+	void setTimingFunctionParameters( const TimingFunction::Parameters& timingFunctionParameters );
+
 	void setDirection( const AnimationDirection& value );
 
 	void setFillMode( const AnimationFillMode& value );
@@ -87,7 +94,9 @@ class EE_API AnimationDefinition {
 	Time mDuration = Time::Zero;
 	Int32 mIterations = 1; /* -1 == "infinite" */
 	Ease::Interpolation mTimingFunction = Ease::Interpolation::Linear;
-	std::vector<double> mTimingFunctionParameters{};
+	TimingFunction::Parameters mTimingFunctionParameters{};
+	mutable std::vector<double> mTimingFunctionParametersVector;
+	mutable bool mTimingFunctionParametersVectorValid{ false };
 	AnimationDirection mDirection = Normal;
 	AnimationFillMode mFillMode = None;
 	bool mPaused = false;
@@ -98,7 +107,7 @@ inline bool operator==( const AnimationDefinition& a, const AnimationDefinition&
 		   a.getDelay() == b.getDelay() && a.getDirection() == b.getDirection() &&
 		   a.isPaused() == b.isPaused() && a.getIterations() == b.getIterations() &&
 		   a.getName() == b.getName() &&
-		   a.getTimingFunctionParameters() == b.getTimingFunctionParameters();
+		   a.getTimingFunctionParametersInline() == b.getTimingFunctionParametersInline();
 }
 
 inline bool operator!=( const AnimationDefinition& a, const AnimationDefinition& b ) {
diff --git a/include/eepp/ui/css/elementdefinition.hpp b/include/eepp/ui/css/elementdefinition.hpp
index 4546cbeb4..bc7267cae 100644
--- a/include/eepp/ui/css/elementdefinition.hpp
+++ b/include/eepp/ui/css/elementdefinition.hpp
@@ -5,6 +5,7 @@
 #include <eepp/ui/css/propertyidset.hpp>
 #include <eepp/ui/css/stylesheetproperty.hpp>
 #include <eepp/ui/css/stylesheetstyle.hpp>
+#include <eepp/ui/css/transitiondefinition.hpp>
 
 namespace EE { namespace UI { namespace CSS {
 
@@ -22,6 +23,8 @@ class EE_API ElementDefinition : NonCopyable {
 
 	const std::vector<const CSS::StyleSheetProperty*>& getTransitionProperties() const;
 
+	const ComputedTransitions& getTransitions() const;
+
 	const std::vector<const CSS::StyleSheetProperty*>& getAnimationProperties() const;
 
 	const StyleSheetVariables& getVariables() const;
@@ -38,6 +41,7 @@ class EE_API ElementDefinition : NonCopyable {
 	StyleSheetVariables mVariables;
 	PropertyIdSet mPropertyIds;
 	std::vector<const CSS::StyleSheetProperty*> mTransitionProperties;
+	ComputedTransitions mTransitions;
 	std::vector<const CSS::StyleSheetProperty*> mAnimationProperties;
 	bool mStructurallyVolatile;
 
diff --git a/include/eepp/ui/css/stylesheetlength.hpp b/include/eepp/ui/css/stylesheetlength.hpp
index b82db33ce..c10fbf283 100644
--- a/include/eepp/ui/css/stylesheetlength.hpp
+++ b/include/eepp/ui/css/stylesheetlength.hpp
@@ -58,12 +58,21 @@ class EE_API StyleSheetLength {
 
 	static StyleSheetLength fromString( const std::string& str, const Float& defaultValue = 0,
 										bool pxAsDp = false );
+	static StyleSheetLength fromString( std::string_view str, const Float& defaultValue = 0,
+										bool pxAsDp = false );
+	static StyleSheetLength fromString( const char* str, const Float& defaultValue = 0,
+										bool pxAsDp = false ) {
+		return fromString( std::string_view{ str }, defaultValue, pxAsDp );
+	}
 
 	StyleSheetLength();
 
 	StyleSheetLength( const Float& val, const Unit& unit );
 
 	StyleSheetLength( const std::string& val, const Float& defaultValue = 0 );
+	StyleSheetLength( std::string_view val, const Float& defaultValue = 0 );
+	StyleSheetLength( const char* val, const Float& defaultValue = 0 ) :
+		StyleSheetLength( std::string_view{ val }, defaultValue ) {}
 
 	StyleSheetLength( const StyleSheetLength& val );
 
@@ -98,7 +107,7 @@ class EE_API StyleSheetLength {
   protected:
 	static bool isFunctionString( std::string_view str );
 
-	static bool parseFunction( const std::string& str, Unit& outUnit, Arguments& outArgs );
+	static bool parseFunction( std::string_view str, Unit& outUnit, Arguments& outArgs );
 
 	Float resolveFunction( const Float& parentSize, const Sizef& viewSize, const Float& displayDpi,
 						   const Float& elFontSize, const Float& globalFontSize,
diff --git a/include/eepp/ui/css/stylesheetpropertyanimation.hpp b/include/eepp/ui/css/stylesheetpropertyanimation.hpp
index 20873f942..af7dca09e 100644
--- a/include/eepp/ui/css/stylesheetpropertyanimation.hpp
+++ b/include/eepp/ui/css/stylesheetpropertyanimation.hpp
@@ -26,7 +26,7 @@ class EE_API StyleSheetPropertyAnimation : public Action {
 							   const PropertyDefinition* property, const std::string& startValue,
 							   const std::string& endValue,
 							   const Ease::Interpolation& timingFunction,
-							   const std::vector<double> timingFunctionParameters,
+							   const TimingFunction::Parameters& timingFunctionParameters,
 							   const Uint32& propertyIndex, const bool& isDone );
 
 	static StyleSheetPropertyAnimation* fromAnimationKeyframes(
@@ -48,6 +48,13 @@ class EE_API StyleSheetPropertyAnimation : public Action {
 		 const std::vector<double>& timingFunctionParameters,
 		 const AnimationOrigin& animationOrigin );
 
+	static StyleSheetPropertyAnimation*
+	New( const PropertyDefinition* property, const std::string& startValue,
+		 const std::string& endValue, const Uint32& propertyIndex, const Time& duration,
+		 const Time& delay, const Ease::Interpolation& timingFunction,
+		 const TimingFunction::Parameters& timingFunctionParameters,
+		 const AnimationOrigin& animationOrigin );
+
 	void start() override;
 
 	void stop() override;
@@ -87,8 +94,8 @@ class EE_API StyleSheetPropertyAnimation : public Action {
   protected:
 	AnimationDefinition mAnimation;
 	const PropertyDefinition* mPropertyDef;
-	std::vector<std::string> mStates;
-	std::vector<Float> mAnimationStepsTime;
+	SmallVector<std::string, 4> mStates;
+	SmallVector<Float, 4> mAnimationStepsTime;
 	Time mRealElapsed;
 	Time mElapsed;
 	Int32 mPendingIterations;
@@ -103,6 +110,13 @@ class EE_API StyleSheetPropertyAnimation : public Action {
 								 std::vector<Float> animationStepsTime, const Uint32& propertyIndex,
 								 const AnimationOrigin& animationOrigin );
 
+	StyleSheetPropertyAnimation( const AnimationDefinition& animation,
+								 const PropertyDefinition* propertyDef,
+								 SmallVector<std::string, 4> states,
+								 SmallVector<Float, 4> animationStepsTime,
+								 const Uint32& propertyIndex,
+								 const AnimationOrigin& animationOrigin );
+
 	void onStart() override;
 
 	void onUpdate( const Time& time ) override;
diff --git a/include/eepp/ui/css/timingfunction.hpp b/include/eepp/ui/css/timingfunction.hpp
index 62cf4419c..b34387e73 100644
--- a/include/eepp/ui/css/timingfunction.hpp
+++ b/include/eepp/ui/css/timingfunction.hpp
@@ -1,20 +1,28 @@
 #ifndef EE_UI_CSS_TIMINGFUNCTION_HPP
 #define EE_UI_CSS_TIMINGFUNCTION_HPP
 
+#include <eepp/core/small_vector.hpp>
 #include <eepp/core/string.hpp>
 #include <eepp/math/ease.hpp>
 
-using namespace EE;
 using namespace EE::Math;
 
 namespace EE { namespace UI { namespace CSS {
 
 class EE_API TimingFunction {
   public:
+	using Parameters = SmallVector<double, 4>;
+
 	static TimingFunction parse( std::string timingFunction );
 
+	static TimingFunction parse( std::string_view timingFunction );
+
+	static TimingFunction parse( const char* timingFunction ) {
+		return parse( std::string_view{ timingFunction } );
+	}
+
 	Ease::Interpolation interpolation{ Ease::None };
-	std::vector<double> parameters;
+	Parameters parameters;
 };
 
 }}} // namespace EE::UI::CSS
diff --git a/include/eepp/ui/css/transitiondefinition.hpp b/include/eepp/ui/css/transitiondefinition.hpp
index cc922e9d1..1ebe0a1a1 100644
--- a/include/eepp/ui/css/transitiondefinition.hpp
+++ b/include/eepp/ui/css/transitiondefinition.hpp
@@ -1,9 +1,11 @@
 #ifndef EE_UI_CSS_TRANSITIONDEFINITION_HPP
 #define EE_UI_CSS_TRANSITIONDEFINITION_HPP
 
+#include <eepp/core/small_vector.hpp>
 #include <eepp/math/ease.hpp>
 #include <eepp/system/time.hpp>
 #include <eepp/ui/css/stylesheetproperty.hpp>
+#include <eepp/ui/css/timingfunction.hpp>
 #include <vector>
 
 using namespace EE::Math;
@@ -37,6 +39,33 @@ class EE_API TransitionDefinition {
 
 typedef UnorderedMap<std::string, TransitionDefinition> TransitionsMap;
 
+/** Compact transition data used by computed element definitions. It owns no strings and keeps
+ * the complete CSS timing-function payload inline. */
+struct ComputedTransitionDefinition {
+	String::HashType propertyNameHash{ 0 };
+	Ease::Interpolation timingFunction{ Ease::Linear };
+	TimingFunction::Parameters timingFunctionParameters;
+	Time delay{ Time::Zero };
+	Time duration{ Time::Zero };
+};
+
+class EE_API ComputedTransitions {
+  public:
+	static ComputedTransitions
+	parse( const std::vector<const StyleSheetProperty*>& styleSheetProperties );
+
+	const ComputedTransitionDefinition* get( String::HashType propertyNameHash ) const;
+
+	bool empty() const { return mTransitions.empty(); }
+
+	std::size_t size() const { return mTransitions.size(); }
+
+  private:
+	SmallVector<ComputedTransitionDefinition, 4> mTransitions;
+
+	void set( const ComputedTransitionDefinition& transition );
+};
+
 }}} // namespace EE::UI::CSS
 
 #endif
diff --git a/include/eepp/ui/uinodedrawable.hpp b/include/eepp/ui/uinodedrawable.hpp
index c589eedb7..01cdbf867 100644
--- a/include/eepp/ui/uinodedrawable.hpp
+++ b/include/eepp/ui/uinodedrawable.hpp
@@ -96,7 +96,7 @@ class EE_API UINodeDrawable : public Drawable {
 
 		Sizef calcDrawableSize( const std::string& drawableSizeEq );
 
-		Vector2f calcPosition( std::string positionXEq, std::string positionYEq );
+		Vector2f calcPosition( const std::string& positionXEq, const std::string& positionYEq );
 
 		const std::string& getPositionX() const;
 
diff --git a/include/eepp/ui/uistyle.hpp b/include/eepp/ui/uistyle.hpp
index 943028070..58d3bd14c 100644
--- a/include/eepp/ui/uistyle.hpp
+++ b/include/eepp/ui/uistyle.hpp
@@ -100,7 +100,6 @@ class EE_API UIStyle : public UIState {
 	std::shared_ptr<CSS::StyleSheetStyle> mElementStyle;
 	std::shared_ptr<CSS::ElementDefinition> mGlobalDefinition;
 	std::shared_ptr<CSS::ElementDefinition> mDefinition;
-	CSS::TransitionsMap mTransitions;
 	CSS::AnimationsMap mAnimations;
 	UnorderedSet<UIWidget*> mRelatedWidgets;
 	UnorderedSet<UIWidget*> mSubscribedWidgets;
diff --git a/src/eepp/core/memorymanager.cpp b/src/eepp/core/memorymanager.cpp
index 9bb4d67a3..75b3b39f4 100644
--- a/src/eepp/core/memorymanager.cpp
+++ b/src/eepp/core/memorymanager.cpp
@@ -18,7 +18,7 @@ using namespace EE::Window;
 
 namespace EE {
 
-AllocatedPointer::AllocatedPointer( void* data, const std::string& file, int line, size_t memory,
+AllocatedPointer::AllocatedPointer( void* data, const char* file, int line, size_t memory,
 									bool track, bool globalAllocation ) {
 	mData = data;
 	mFile = file;
@@ -75,7 +75,7 @@ void* MemoryManager::addPointerInPlace( void* place, const AllocatedPointer& aAl
 	AllocatedPointerMapIt it = state.pointers.find( place );
 
 	if ( it != state.pointers.end() ) {
-		removePointer( place, aAllocatedPointer.mFile.c_str(), aAllocatedPointer.mLine );
+		removePointer( place, aAllocatedPointer.mFile, aAllocatedPointer.mLine );
 	}
 
 	return addPointer( aAllocatedPointer );
@@ -110,7 +110,7 @@ void* MemoryManager::addPointer( const AllocatedPointer& aAllocatedPointer ) {
 
 	if ( aAllocatedPointer.mTrack )
 		eePRINTL( "Allocating pointer %p at '%s' %d", aAllocatedPointer.mData,
-				  aAllocatedPointer.mFile.c_str(), aAllocatedPointer.mLine );
+				  aAllocatedPointer.mFile, aAllocatedPointer.mLine );
 
 	return aAllocatedPointer.mData;
 }
@@ -123,7 +123,7 @@ void* MemoryManager::reallocPointer( void* data, const AllocatedPointer& aAlloca
 	AllocatedPointerMapIt it = state.pointers.find( data );
 
 	if ( it != state.pointers.end() && it->second.mTrack )
-		eePRINTL( "Realloc pointer %p at '%s' %d", data, aAllocatedPointer.mFile.c_str(),
+		eePRINTL( "Realloc pointer %p at '%s' %d", data, aAllocatedPointer.mFile,
 				  aAllocatedPointer.mLine );
 
 	if ( it == state.pointers.end() )
@@ -131,10 +131,10 @@ void* MemoryManager::reallocPointer( void* data, const AllocatedPointer& aAlloca
 
 	if ( aAllocatedPointer.mTrack )
 		eePRINTL( "Reallocating pointer %p at '%s' %d", aAllocatedPointer.mData,
-				  aAllocatedPointer.mFile.c_str(), aAllocatedPointer.mLine );
+				  aAllocatedPointer.mFile, aAllocatedPointer.mLine );
 
 	if ( it->first != aAllocatedPointer.mData ) {
-		removePointer( data, aAllocatedPointer.mFile.c_str(), aAllocatedPointer.mLine );
+		removePointer( data, aAllocatedPointer.mFile, aAllocatedPointer.mLine );
 		addPointer( aAllocatedPointer );
 	} else {
 		state.totalMemoryUsage -= it->second.mMemory;
@@ -310,7 +310,7 @@ void MemoryManager::showResults() {
 
 			char address[2 + sizeof( void* ) * 2 + 1];
 			snprintf( address, sizeof( address ), "%p", ap.mData );
-			leaks.add_row( { address, ap.mFile, std::to_string( ap.mLine ),
+			leaks.add_row( { address, std::string{ ap.mFile }, std::to_string( ap.mLine ),
 							 FileSystem::sizeToString( static_cast<Int64>( ap.mMemory ) ) } );
 		}
 
@@ -320,7 +320,7 @@ void MemoryManager::showResults() {
 	auto allocationLocation = []( const AllocatedPointer& allocation ) {
 		return allocation.mData == nullptr
 				   ? std::string( "-" )
-				   : allocation.mFile + ":" + std::to_string( allocation.mLine );
+				   : std::string{ allocation.mFile } + ":" + std::to_string( allocation.mLine );
 	};
 
 	tabulate::Table summary;
diff --git a/src/eepp/scene/action.cpp b/src/eepp/scene/action.cpp
index f875d9e9c..4cbd4c10d 100644
--- a/src/eepp/scene/action.cpp
+++ b/src/eepp/scene/action.cpp
@@ -1,8 +1,138 @@
+#include <array>
+#include <cstdlib>
 #include <eepp/scene/action.hpp>
 #include <eepp/scene/node.hpp>
+#include <mutex>
+#include <new>
 
 namespace EE { namespace Scene {
 
+namespace {
+
+class ActionPool {
+  public:
+	static ActionPool& instance();
+
+	void* allocate( std::size_t size ) {
+		const std::size_t classIndex = findClass( size );
+		if ( classIndex == NumClasses )
+			return allocateLarge( size );
+
+		std::lock_guard<std::mutex> lock( mMutex );
+		SizeClass& sizeClass = mClasses[classIndex];
+		if ( nullptr == sizeClass.freeList )
+			allocatePage( classIndex );
+
+		BlockHeader* block = sizeClass.freeList;
+		sizeClass.freeList = block->next;
+		block->classIndex = static_cast<Uint16>( classIndex );
+		return block + 1;
+	}
+
+	void deallocate( void* ptr ) noexcept {
+		if ( nullptr == ptr )
+			return;
+
+		BlockHeader* block = static_cast<BlockHeader*>( ptr ) - 1;
+		if ( block->classIndex == LargeAllocation ) {
+			std::free( block );
+			return;
+		}
+
+		std::lock_guard<std::mutex> lock( mMutex );
+		SizeClass& sizeClass = mClasses[block->classIndex];
+		block->next = sizeClass.freeList;
+		sizeClass.freeList = block;
+	}
+
+  private:
+	static constexpr std::array<std::size_t, 9> ClassSizes = { 64,	96,	 128, 192, 256,
+															   384, 512, 768, 1024 };
+	static constexpr std::size_t NumClasses = ClassSizes.size();
+	static constexpr Uint16 LargeAllocation = static_cast<Uint16>( -1 );
+	static constexpr std::size_t BlocksPerPage = 64;
+
+	struct alignas( std::max_align_t ) BlockHeader {
+		BlockHeader* next;
+		Uint16 classIndex;
+	};
+
+	struct Page {
+		Page* next;
+	};
+
+	struct SizeClass {
+		BlockHeader* freeList{ nullptr };
+		Page* pages{ nullptr };
+	};
+
+	std::array<SizeClass, NumClasses> mClasses;
+	std::mutex mMutex;
+
+	static constexpr std::size_t alignUp( std::size_t size ) {
+		return ( size + alignof( std::max_align_t ) - 1 ) & ~( alignof( std::max_align_t ) - 1 );
+	}
+
+	static std::size_t findClass( std::size_t size ) {
+		for ( std::size_t i = 0; i < NumClasses; ++i ) {
+			if ( size <= ClassSizes[i] )
+				return i;
+		}
+		return NumClasses;
+	}
+
+	void allocatePage( std::size_t classIndex ) {
+		SizeClass& sizeClass = mClasses[classIndex];
+		const std::size_t stride = alignUp( sizeof( BlockHeader ) + ClassSizes[classIndex] );
+		const std::size_t bytes = alignUp( sizeof( Page ) ) + stride * BlocksPerPage;
+		Page* page = static_cast<Page*>( std::malloc( bytes ) );
+		if ( nullptr == page )
+			throw std::bad_alloc();
+
+		page->next = sizeClass.pages;
+		sizeClass.pages = page;
+		char* storage = reinterpret_cast<char*>( page ) + alignUp( sizeof( Page ) );
+		for ( std::size_t i = 0; i < BlocksPerPage; ++i ) {
+			BlockHeader* block = reinterpret_cast<BlockHeader*>( storage + stride * i );
+			block->classIndex = static_cast<Uint16>( classIndex );
+			block->next = sizeClass.freeList;
+			sizeClass.freeList = block;
+		}
+	}
+
+	static void* allocateLarge( std::size_t size ) {
+		BlockHeader* block =
+			static_cast<BlockHeader*>( std::malloc( sizeof( BlockHeader ) + size ) );
+		if ( nullptr == block )
+			throw std::bad_alloc();
+		block->classIndex = LargeAllocation;
+		block->next = nullptr;
+		return block + 1;
+	}
+};
+
+ActionPool& ActionPool::instance() {
+	// Actions can be owned by globals initialized before the first action allocation. Keeping the
+	// pool alive until process exit avoids a static-destruction-order race with those owners.
+	alignas( ActionPool ) static unsigned char storage[sizeof( ActionPool )];
+	static ActionPool* pool = new ( storage ) ActionPool;
+	return *pool;
+}
+
+} // namespace
+
+void* Action::operator new( std::size_t size ) {
+	return ActionPool::instance().allocate( size );
+}
+
+void Action::operator delete( void* ptr ) noexcept {
+	ActionPool::instance().deallocate( ptr );
+}
+
+void Action::operator delete( void* ptr, std::size_t ) noexcept {
+	ActionPool::instance().deallocate( ptr );
+}
+
 Action::~Action() {
 	sendEvent( ActionType::OnDelete );
 }
@@ -53,7 +183,7 @@ Action* Action::reverse() const {
 Uint32 Action::addEventListener( const ActionType& actionType, const ActionCallback& callback ) {
 	mNumCallBacks++;
 
-	mCallbacks[actionType][mNumCallBacks] = callback;
+	mCallbacks.emplace_back( ActionCallbackEntry{ actionType, mNumCallBacks, callback } );
 
 	return mNumCallBacks;
 }
@@ -65,22 +195,23 @@ Action* Action::on( const Action::ActionType& actionType, const Action::ActionCa
 
 void Action::removeEventListener( const Uint32& callbackId ) {
 	for ( auto it = mCallbacks.begin(); it != mCallbacks.end(); ++it ) {
-		UnorderedMap<Uint32, ActionCallback>& event = it->second;
-
-		if ( event.erase( callbackId ) )
+		if ( it->id == callbackId ) {
+			mCallbacks.erase( it );
 			break;
+		}
 	}
 }
 
 void Action::sendEvent( const ActionType& actionType ) {
-	if ( 0 != mCallbacks.count( actionType ) ) {
-		auto event = mCallbacks[actionType];
-
-		if ( !event.empty() ) {
-			for ( auto it = event.begin(); it != event.end(); ++it )
-				it->second( this, actionType );
-		}
+	// Callbacks are allowed to mutate listener registration. Preserve the previous snapshot
+	// semantics while keeping the common callback count in inline storage.
+	SmallVector<ActionCallback, 4> callbacks;
+	for ( const auto& callback : mCallbacks ) {
+		if ( callback.type == actionType )
+			callbacks.emplace_back( callback.callback );
 	}
+	for ( auto& callback : callbacks )
+		callback( this, actionType );
 }
 
 void Action::onStart() {}
diff --git a/src/eepp/scene/actionmanager.cpp b/src/eepp/scene/actionmanager.cpp
index 190c739cd..8c89ef5c6 100644
--- a/src/eepp/scene/actionmanager.cpp
+++ b/src/eepp/scene/actionmanager.cpp
@@ -81,12 +81,21 @@ std::vector<Action*> ActionManager::getActionsByTagFromTarget( Node* target,
 	return actions;
 }
 
+void ActionManager::getActionsByTagFromTarget( Node* target, const Action::UniqueID& tag,
+											   SmallVector<Action*, 4>& actions ) {
+	Lock l( mMutex );
+	for ( Action* action : mActions ) {
+		if ( action->getTarget() == target && action->getTag() == tag )
+			actions.emplace_back( action );
+	}
+}
+
 bool ActionManager::removeActionByTag( const Action::UniqueID& tag ) {
 	return removeAction( getActionByTag( tag ) );
 }
 
 bool ActionManager::removeActionsByTagFromTarget( Node* target, const Action::UniqueID& tag ) {
-	std::vector<Action*> removeList;
+	ActionList removeList;
 
 	{
 		Lock l( mMutex );
@@ -226,7 +235,7 @@ bool ActionManager::removeActions( const std::vector<Action*>& actions ) {
 }
 
 bool ActionManager::removeAllActionsFromTarget( Node* target ) {
-	std::vector<Action*> removeList;
+	ActionList removeList;
 
 	{
 		Lock l( mMutex );
diff --git a/src/eepp/scene/actions/runnable.cpp b/src/eepp/scene/actions/runnable.cpp
index 22da9e534..55e9f8d66 100644
--- a/src/eepp/scene/actions/runnable.cpp
+++ b/src/eepp/scene/actions/runnable.cpp
@@ -4,7 +4,7 @@
 namespace EE { namespace Scene { namespace Actions {
 
 Runnable* Runnable::New( RunnableFunc callback, const Time& time, bool loop ) {
-	return eeNew( Runnable, ( callback, time, loop ) );
+	return eeNew( Runnable, ( std::move( callback ), time, loop ) );
 }
 
 Runnable::Runnable( Runnable::RunnableFunc callback, const Time& time, bool loop ) :
diff --git a/src/eepp/scene/actions/sequence.cpp b/src/eepp/scene/actions/sequence.cpp
index d8ee28302..d2bbbd339 100644
--- a/src/eepp/scene/actions/sequence.cpp
+++ b/src/eepp/scene/actions/sequence.cpp
@@ -7,41 +7,45 @@ Sequence* Sequence::New( const std::vector<Action*> sequence ) {
 }
 
 Sequence* Sequence::New( Action* action, Action* action2 ) {
-	return New( {action, action2} );
+	return eeNew( Sequence, ( ActionContainer{ action, action2 } ) );
 }
 
 Sequence* Sequence::New( Action* action, Action* action2, Action* action3 ) {
-	return New( {action, action2, action3} );
+	return eeNew( Sequence, ( ActionContainer{ action, action2, action3 } ) );
 }
 
 Sequence* Sequence::New( Action* action, Action* action2, Action* action3, Action* action4 ) {
-	return New( {action, action2, action3, action4} );
+	return eeNew( Sequence, ( ActionContainer{ action, action2, action3, action4 } ) );
 }
 
 Sequence* Sequence::New( Action* action, Action* action2, Action* action3, Action* action4,
 						 Action* action5 ) {
-	return New( {action, action2, action3, action4, action5} );
+	return eeNew( Sequence, ( ActionContainer{ action, action2, action3, action4, action5 } ) );
 }
 
 Sequence* Sequence::New( Action* action, Action* action2, Action* action3, Action* action4,
 						 Action* action5, Action* action6 ) {
-	return New( {action, action2, action3, action4, action5, action6} );
+	return eeNew( Sequence,
+				  ( ActionContainer{ action, action2, action3, action4, action5, action6 } ) );
 }
 
 Sequence* Sequence::New( Action* action, Action* action2, Action* action3, Action* action4,
 						 Action* action5, Action* action6, Action* action7 ) {
-	return New( {action, action2, action3, action4, action5, action6, action7} );
+	return eeNew( Sequence, ( ActionContainer{ action, action2, action3, action4, action5, action6,
+											   action7 } ) );
 }
 
 Sequence* Sequence::New( Action* action, Action* action2, Action* action3, Action* action4,
 						 Action* action5, Action* action6, Action* action7, Action* action8 ) {
-	return New( {action, action2, action3, action4, action5, action6, action7, action8} );
+	return eeNew( Sequence, ( ActionContainer{ action, action2, action3, action4, action5, action6,
+											   action7, action8 } ) );
 }
 
 Sequence* Sequence::New( Action* action, Action* action2, Action* action3, Action* action4,
 						 Action* action5, Action* action6, Action* action7, Action* action8,
 						 Action* action9 ) {
-	return New( {action, action2, action3, action4, action5, action6, action7, action8, action9} );
+	return eeNew( Sequence, ( ActionContainer{ action, action2, action3, action4, action5, action6,
+											   action7, action8, action9 } ) );
 }
 
 void Sequence::start() {
@@ -102,17 +106,17 @@ Time Sequence::getTotalTime() {
 }
 
 Action* Sequence::clone() const {
-	return Sequence::New( mSequence );
+	return eeNew( Sequence, ( mSequence ) );
 }
 
 Action* Sequence::reverse() const {
-	std::vector<Action*> reversed;
+	ActionContainer reversed;
 
 	for ( auto it = mSequence.rbegin(); it != mSequence.rend(); ++it ) {
 		reversed.push_back( *it );
 	}
 
-	return Sequence::New( reversed );
+	return eeNew( Sequence, ( std::move( reversed ) ) );
 }
 
 Sequence::~Sequence() {
@@ -122,6 +126,9 @@ Sequence::~Sequence() {
 	}
 }
 
-Sequence::Sequence( const std::vector<Action*> sequence ) : mSequence( sequence ), mCurPos( 0 ) {}
+Sequence::Sequence( const std::vector<Action*> sequence ) :
+	mSequence( sequence.begin(), sequence.end() ), mCurPos( 0 ) {}
+
+Sequence::Sequence( ActionContainer sequence ) : mSequence( std::move( sequence ) ), mCurPos( 0 ) {}
 
 }}} // namespace EE::Scene::Actions
diff --git a/src/eepp/scene/actions/spawn.cpp b/src/eepp/scene/actions/spawn.cpp
index 8eb4c7df8..42ebc8cd7 100644
--- a/src/eepp/scene/actions/spawn.cpp
+++ b/src/eepp/scene/actions/spawn.cpp
@@ -7,41 +7,45 @@ Spawn* Spawn::New( const std::vector<Action*> spawn ) {
 }
 
 Spawn* Spawn::New( Action* action, Action* action2 ) {
-	return New( {action, action2} );
+	return eeNew( Spawn, ( ActionContainer{ action, action2 } ) );
 }
 
 Spawn* Spawn::New( Action* action, Action* action2, Action* action3 ) {
-	return New( {action, action2, action3} );
+	return eeNew( Spawn, ( ActionContainer{ action, action2, action3 } ) );
 }
 
 Spawn* Spawn::New( Action* action, Action* action2, Action* action3, Action* action4 ) {
-	return New( {action, action2, action3, action4} );
+	return eeNew( Spawn, ( ActionContainer{ action, action2, action3, action4 } ) );
 }
 
 Spawn* Spawn::New( Action* action, Action* action2, Action* action3, Action* action4,
 				   Action* action5 ) {
-	return New( {action, action2, action3, action4, action5} );
+	return eeNew( Spawn, ( ActionContainer{ action, action2, action3, action4, action5 } ) );
 }
 
 Spawn* Spawn::New( Action* action, Action* action2, Action* action3, Action* action4,
 				   Action* action5, Action* action6 ) {
-	return New( {action, action2, action3, action4, action5, action6} );
+	return eeNew( Spawn,
+				  ( ActionContainer{ action, action2, action3, action4, action5, action6 } ) );
 }
 
 Spawn* Spawn::New( Action* action, Action* action2, Action* action3, Action* action4,
 				   Action* action5, Action* action6, Action* action7 ) {
-	return New( {action, action2, action3, action4, action5, action6, action7} );
+	return eeNew( Spawn, ( ActionContainer{ action, action2, action3, action4, action5, action6,
+											action7 } ) );
 }
 
 Spawn* Spawn::New( Action* action, Action* action2, Action* action3, Action* action4,
 				   Action* action5, Action* action6, Action* action7, Action* action8 ) {
-	return New( {action, action2, action3, action4, action5, action6, action7, action8} );
+	return eeNew( Spawn, ( ActionContainer{ action, action2, action3, action4, action5, action6,
+											action7, action8 } ) );
 }
 
 Spawn* Spawn::New( Action* action, Action* action2, Action* action3, Action* action4,
 				   Action* action5, Action* action6, Action* action7, Action* action8,
 				   Action* action9 ) {
-	return New( {action, action2, action3, action4, action5, action6, action7, action8, action9} );
+	return eeNew( Spawn, ( ActionContainer{ action, action2, action3, action4, action5, action6,
+											action7, action8, action9 } ) );
 }
 
 void Spawn::start() {
@@ -102,17 +106,17 @@ Time Spawn::getTotalTime() {
 }
 
 Action* Spawn::clone() const {
-	return Spawn::New( mSpawn );
+	return eeNew( Spawn, ( mSpawn ) );
 }
 
 Action* Spawn::reverse() const {
-	std::vector<Action*> reversed;
+	ActionContainer reversed;
 
 	for ( auto it = mSpawn.rbegin(); it != mSpawn.rend(); ++it ) {
 		reversed.push_back( *it );
 	}
 
-	return Spawn::New( reversed );
+	return eeNew( Spawn, ( std::move( reversed ) ) );
 }
 
 Spawn::~Spawn() {
@@ -122,6 +126,9 @@ Spawn::~Spawn() {
 	}
 }
 
-Spawn::Spawn( const std::vector<Action*> spawn ) : mSpawn( spawn ), mAllDone( false ) {}
+Spawn::Spawn( const std::vector<Action*> spawn ) :
+	mSpawn( spawn.begin(), spawn.end() ), mAllDone( false ) {}
+
+Spawn::Spawn( ActionContainer spawn ) : mSpawn( std::move( spawn ) ), mAllDone( false ) {}
 
 }}} // namespace EE::Scene::Actions
diff --git a/src/eepp/scene/node.cpp b/src/eepp/scene/node.cpp
index 7e471cf9b..86773024d 100644
--- a/src/eepp/scene/node.cpp
+++ b/src/eepp/scene/node.cpp
@@ -1526,6 +1526,10 @@ std::vector<Action*> Node::getActionsByTag( const Action::UniqueID& tag ) {
 	return getActionManager()->getActionsByTagFromTarget( this, tag );
 }
 
+void Node::getActionsByTag( const Action::UniqueID& tag, SmallVector<Action*, 4>& actions ) {
+	getActionManager()->getActionsByTagFromTarget( this, tag, actions );
+}
+
 void Node::clearActions() {
 	getActionManager()->removeAllActionsFromTarget( this );
 }
diff --git a/src/eepp/system/color.cpp b/src/eepp/system/color.cpp
index aa23cd405..c891319cd 100644
--- a/src/eepp/system/color.cpp
+++ b/src/eepp/system/color.cpp
@@ -106,10 +106,7 @@ static bool tryParseModernRgbRgba( std::string_view paramsStr, Color& outColor )
 }
 
 static bool parseHslHue( Float& out, std::string_view tok ) {
-	while ( !tok.empty() && ( tok.front() == ' ' || tok.front() == '\t' ) )
-		tok.remove_prefix( 1 );
-	while ( !tok.empty() && ( tok.back() == ' ' || tok.back() == '\t' ) )
-		tok.remove_suffix( 1 );
+	tok = String::trim( tok, " \t" );
 	if ( tok.empty() )
 		return false;
 	if ( tok.size() == 4 && ( std::strncmp( tok.data(), "none", 4 ) == 0 ||
@@ -133,10 +130,7 @@ static bool parseHslHue( Float& out, std::string_view tok ) {
 }
 
 static bool parseHslPercentOrNumber( Float& out, std::string_view tok ) {
-	while ( !tok.empty() && ( tok.front() == ' ' || tok.front() == '\t' ) )
-		tok.remove_prefix( 1 );
-	while ( !tok.empty() && ( tok.back() == ' ' || tok.back() == '\t' ) )
-		tok.remove_suffix( 1 );
+	tok = String::trim( tok, " \t" );
 	if ( tok.empty() )
 		return false;
 	if ( tok.size() == 4 && ( std::strncmp( tok.data(), "none", 4 ) == 0 ||
diff --git a/src/eepp/system/functionstring.cpp b/src/eepp/system/functionstring.cpp
index 42c2d962a..b95924a7e 100644
--- a/src/eepp/system/functionstring.cpp
+++ b/src/eepp/system/functionstring.cpp
@@ -3,128 +3,56 @@
 #include <eepp/system/functionstring.hpp>
 
 #include <string>
-#include <type_traits>
 
 namespace EE { namespace System {
 
-template <typename StringType> FunctionString FunctionString::parse( StringType function ) {
-	using CharType = typename StringType::value_type;
-
-	size_t funcSep = function.find( '(' );
-	if ( funcSep == StringType::npos )
-		return FunctionString( "", {}, {} );
-
-	auto funcName = String::trim( function.substr( 0, funcSep ) );
+FunctionString FunctionString::parseOwned( std::string_view function ) {
+	View view = parseView( function );
+	if ( view.isEmpty() )
+		return {};
 	Parameters funcParameters;
 	TypeStringVector typeStringData;
-
-	auto parametersString = function.substr( funcSep + 1 );
-	size_t paramClose = parametersString.find_last_of( ')' );
-	if ( paramClose == StringType::npos )
-		return FunctionString( "", {}, {} );
-
-	parametersString = parametersString.substr( 0, paramClose );
-
-	bool stateParsingString = false;
-	std::basic_string<CharType> buffer;
-	CharType prevChar = 0;
-	CharType quoteChar = 0;
-
-	bool currentParamIsString = false;
-	int parenDepth = 0;
-
-	auto pushBufferToParams = [&]() {
-		if constexpr ( std::is_same_v<CharType, char> ) {
-			if ( !currentParamIsString )
-				String::trimInPlace( buffer );
-			funcParameters.push_back( buffer );
-		} else {
-			std::string utf8Buffer = String( buffer ).toUtf8();
-			if ( !currentParamIsString )
-				String::trimInPlace( utf8Buffer );
-			funcParameters.push_back( utf8Buffer );
+	view.forEachParameter( [&]( std::string_view parameter, bool wasString ) {
+		std::string owned;
+		owned.reserve( parameter.size() );
+		const char quote = wasString ? function[parameter.data() - function.data() - 1] : 0;
+		for ( std::size_t i = 0; i < parameter.size(); ++i ) {
+			if ( wasString && parameter[i] == '\\' && i + 1 < parameter.size() &&
+				 parameter[i + 1] == quote )
+				continue;
+			owned += parameter[i];
 		}
-		typeStringData.push_back( currentParamIsString );
-		buffer.clear();
-		currentParamIsString = false;
-	};
+		funcParameters.emplace_back( std::move( owned ) );
+		typeStringData.emplace_back( wasString );
+		return true;
+	} );
+	return FunctionString( std::string{ view.getName() }, std::move( funcParameters ),
+						   std::move( typeStringData ) );
+}
 
-	for ( size_t i = 0; i < parametersString.length(); ++i ) {
-
-		CharType c = parametersString[i];
-
-		if ( !stateParsingString ) {
-			if ( c == '(' ) {
-				parenDepth++;
-				buffer += c;
-			} else if ( c == ')' ) {
-				if ( parenDepth == 0 )
-					break;
-				if ( parenDepth > 0 )
-					parenDepth--;
-				buffer += c;
-			} else if ( c == ',' ) {
-				if ( parenDepth == 0 ) {
-					// Add param if we either accumulated characters or actively parsed an empty
-					// string parameter.
-					if ( !buffer.empty() || currentParamIsString ) {
-						pushBufferToParams();
-					}
-				} else {
-					buffer += c;
-				}
-			} else if ( c == '"' || c == '\'' ) {
-				stateParsingString = true;
-				quoteChar = c;
-				if ( parenDepth == 0 && buffer.empty() ) {
-					currentParamIsString = true;
-				} else {
-					buffer += c;
-				}
-			} else if ( c == ' ' ) {
-				if ( buffer.empty() || currentParamIsString )
-					continue;
-				else
-					buffer += c;
-			} else {
-				buffer += c;
-			}
-		} else {
-			if ( c == '\\' && i + 1 < parametersString.length() &&
-				 parametersString[i + 1] == quoteChar ) {
-			} else if ( prevChar != '\\' && c == quoteChar ) {
-				stateParsingString = false;
-				if ( !currentParamIsString ) {
-					buffer += c;
-				}
-			} else {
-				buffer += c;
-			}
-			prevChar = c;
-		}
-	}
-
-	// Add param if we either accumulated characters or actively parsed an empty string parameter.
-	if ( !buffer.empty() || currentParamIsString )
-		pushBufferToParams();
-
-	if constexpr ( std::is_same_v<StringType, std::string> ) {
-		return FunctionString( std::string{ funcName }, funcParameters, typeStringData );
-	} else {
-		return FunctionString( String( funcName ).toUtf8(), funcParameters, typeStringData );
-	}
+FunctionString::View FunctionString::parseView( std::string_view function ) {
+	const std::size_t open = function.find( '(' );
+	if ( open == std::string_view::npos )
+		return {};
+	const std::size_t close = function.rfind( ')' );
+	if ( close == std::string_view::npos || close < open )
+		return {};
+	std::string_view name = String::trim( function.substr( 0, open ), " \t\n\r\f\v" );
+	if ( name.empty() )
+		return {};
+	return View{ name, function.substr( open + 1, close - open - 1 ) };
 }
 
 FunctionString FunctionString::parse( const std::string& function ) {
-	return parse<std::string_view>( std::string_view{ function } );
+	return parseOwned( function );
 }
 
 FunctionString FunctionString::parse( std::string_view function ) {
-	return parse<std::string_view>( function );
+	return parseOwned( function );
 }
 
 FunctionString FunctionString::parse( String::View function ) {
-	return parse<String::View>( function );
+	return parseOwned( String( function ).toUtf8() );
 }
 
 FunctionString::FunctionString( const std::string& name, const Parameters& parameters,
diff --git a/src/eepp/ui/css/animationdefinition.cpp b/src/eepp/ui/css/animationdefinition.cpp
index a0acc68a1..5320566ae 100644
--- a/src/eepp/ui/css/animationdefinition.cpp
+++ b/src/eepp/ui/css/animationdefinition.cpp
@@ -119,7 +119,8 @@ UnorderedMap<std::string, AnimationDefinition> AnimationDefinition::parseAnimati
 						case PropertyId::AnimationTimingFunction: {
 							TimingFunction tf( TimingFunction::parse( val ) );
 							timingFunctions.emplace_back( tf.interpolation );
-							timingFunctionParameters.emplace_back( tf.parameters );
+							timingFunctionParameters.emplace_back( tf.parameters.begin(),
+																   tf.parameters.end() );
 							break;
 						}
 						default:
@@ -256,12 +257,29 @@ const String::HashType& AnimationDefinition::getId() const {
 }
 
 const std::vector<double>& AnimationDefinition::getTimingFunctionParameters() const {
+	if ( !mTimingFunctionParametersVectorValid ) {
+		mTimingFunctionParametersVector.assign( mTimingFunctionParameters.begin(),
+												mTimingFunctionParameters.end() );
+		mTimingFunctionParametersVectorValid = true;
+	}
+	return mTimingFunctionParametersVector;
+}
+
+const TimingFunction::Parameters& AnimationDefinition::getTimingFunctionParametersInline() const {
 	return mTimingFunctionParameters;
 }
 
 void AnimationDefinition::setTimingFunctionParameters(
 	const std::vector<double>& timingFunctionParameters ) {
+	mTimingFunctionParameters.assign( timingFunctionParameters.begin(),
+									  timingFunctionParameters.end() );
+	mTimingFunctionParametersVectorValid = false;
+}
+
+void AnimationDefinition::setTimingFunctionParameters(
+	const TimingFunction::Parameters& timingFunctionParameters ) {
 	mTimingFunctionParameters = timingFunctionParameters;
+	mTimingFunctionParametersVectorValid = false;
 }
 
 const AnimationDefinition::AnimationFillMode& AnimationDefinition::getFillMode() const {
diff --git a/src/eepp/ui/css/elementdefinition.cpp b/src/eepp/ui/css/elementdefinition.cpp
index 6629569d2..22793d118 100644
--- a/src/eepp/ui/css/elementdefinition.cpp
+++ b/src/eepp/ui/css/elementdefinition.cpp
@@ -34,6 +34,10 @@ const std::vector<const StyleSheetProperty*>& ElementDefinition::getTransitionPr
 	return mTransitionProperties;
 }
 
+const ComputedTransitions& ElementDefinition::getTransitions() const {
+	return mTransitions;
+}
+
 const std::vector<const StyleSheetProperty*>& ElementDefinition::getAnimationProperties() const {
 	return mAnimationProperties;
 }
@@ -81,6 +85,7 @@ void ElementDefinition::refresh() {
 	}
 
 	resolveVariables();
+	mTransitions = ComputedTransitions::parse( mTransitionProperties );
 
 	for ( auto& property : mProperties ) {
 		// Only registered properties participate in the dense ID set. Unknown
diff --git a/src/eepp/ui/css/stylesheetlength.cpp b/src/eepp/ui/css/stylesheetlength.cpp
index 8413130c0..7b8a013cb 100644
--- a/src/eepp/ui/css/stylesheetlength.cpp
+++ b/src/eepp/ui/css/stylesheetlength.cpp
@@ -232,6 +232,9 @@ StyleSheetLength::StyleSheetLength( const Float& val, const StyleSheetLength::Un
 	mUnit( unit ), mValue( val ) {}
 
 StyleSheetLength::StyleSheetLength( const std::string& val, const Float& defaultValue ) :
+	StyleSheetLength( fromString( std::string_view{ val }, defaultValue ) ) {}
+
+StyleSheetLength::StyleSheetLength( std::string_view val, const Float& defaultValue ) :
 	StyleSheetLength( fromString( val, defaultValue ) ) {}
 
 StyleSheetLength::StyleSheetLength( const StyleSheetLength& val ) {
@@ -382,9 +385,14 @@ StyleSheetLength& StyleSheetLength::operator=( const StyleSheetLength& val ) {
 
 StyleSheetLength StyleSheetLength::fromString( const std::string& str, const Float& defaultValue,
 											   bool pxAsDp ) {
+	return fromString( std::string_view{ str }, defaultValue, pxAsDp );
+}
+
+StyleSheetLength StyleSheetLength::fromString( std::string_view str, const Float& defaultValue,
+											   bool pxAsDp ) {
 	StyleSheetLength length;
 	length.setValue( defaultValue, Unit::Px );
-	const std::string_view value = String::trim( std::string_view( str ) );
+	const std::string_view value = String::trim( str );
 
 	if ( isFunctionString( value ) ) {
 		Unit funcUnit = Unit::Px;
@@ -470,9 +478,8 @@ bool StyleSheetLength::isFunctionString( std::string_view str ) {
 		   String::istartsWith( str, "max(" ) || String::istartsWith( str, "calc(" );
 }
 
-bool StyleSheetLength::parseFunction( const std::string& str, Unit& outUnit, Arguments& outArgs ) {
-	std::string_view sv( str );
-	std::string_view trimmed = String::trim( sv );
+bool StyleSheetLength::parseFunction( std::string_view str, Unit& outUnit, Arguments& outArgs ) {
+	std::string_view trimmed = String::trim( str );
 
 	if ( String::istartsWith( trimmed, "clamp(" ) ) {
 		outUnit = Unit::Clamp;
diff --git a/src/eepp/ui/css/stylesheetpropertyanimation.cpp b/src/eepp/ui/css/stylesheetpropertyanimation.cpp
index 1aa05e381..a92a055bd 100644
--- a/src/eepp/ui/css/stylesheetpropertyanimation.cpp
+++ b/src/eepp/ui/css/stylesheetpropertyanimation.cpp
@@ -11,7 +11,7 @@ using namespace EE::Math::easing;
 namespace EE { namespace UI { namespace CSS {
 
 inline Float easingFn( const Ease::Interpolation& timingFunction,
-					   const std::vector<double>& timingFunctionParameters, const double& t,
+					   const TimingFunction::Parameters& timingFunctionParameters, const double& t,
 					   const double& b, const double& c, const double& d ) {
 	if ( timingFunction != Ease::Interpolation::CubizBezier )
 		return easingCb[timingFunction]( t, b, c, d );
@@ -24,13 +24,12 @@ inline Float easingFn( const Ease::Interpolation& timingFunction,
 	return t;
 }
 
-void StyleSheetPropertyAnimation::tweenProperty( UIWidget* widget, const Float& normalizedProgress,
-												 const PropertyDefinition* property,
-												 const std::string& startValue,
-												 const std::string& endValue,
-												 const Ease::Interpolation& timingFunction,
-												 const std::vector<double> timingFunctionParameters,
-												 const Uint32& propertyIndex, const bool& isDone ) {
+void StyleSheetPropertyAnimation::tweenProperty(
+	UIWidget* widget, const Float& normalizedProgress, const PropertyDefinition* property,
+	const std::string& startValue, const std::string& endValue,
+	const Ease::Interpolation& timingFunction,
+	const TimingFunction::Parameters& timingFunctionParameters, const Uint32& propertyIndex,
+	const bool& isDone ) {
 	switch ( property->getType() ) {
 		case PropertyType::NumberFloat:
 		case PropertyType::NumberInt: {
@@ -220,13 +219,27 @@ StyleSheetPropertyAnimation* StyleSheetPropertyAnimation::New(
 	const Uint32& propertyIndex, const Time& duration, const Time& delay,
 	const Ease::Interpolation& timingFunction, const std::vector<double>& timingFunctionParameters,
 	const AnimationOrigin& animationOrigin ) {
+	TimingFunction::Parameters parameters;
+	parameters.assign( timingFunctionParameters.begin(), timingFunctionParameters.end() );
+	return New( property, startValue, endValue, propertyIndex, duration, delay, timingFunction,
+				parameters, animationOrigin );
+}
+
+StyleSheetPropertyAnimation*
+StyleSheetPropertyAnimation::New( const PropertyDefinition* property, const std::string& startValue,
+								  const std::string& endValue, const Uint32& propertyIndex,
+								  const Time& duration, const Time& delay,
+								  const Ease::Interpolation& timingFunction,
+								  const TimingFunction::Parameters& timingFunctionParameters,
+								  const AnimationOrigin& animationOrigin ) {
 	AnimationDefinition animation;
 	animation.setDelay( delay );
 	animation.setDuration( duration );
 	animation.setTimingFunction( timingFunction );
 	animation.setTimingFunctionParameters( timingFunctionParameters );
-	return New( animation, property, { startValue, endValue }, { 0, 1 }, propertyIndex,
-				animationOrigin );
+	return eeNew( StyleSheetPropertyAnimation,
+				  ( animation, property, SmallVector<std::string, 4>{ startValue, endValue },
+					SmallVector<Float, 4>{ 0, 1 }, propertyIndex, animationOrigin ) );
 }
 
 StyleSheetPropertyAnimation::StyleSheetPropertyAnimation( const AnimationDefinition& animation,
@@ -237,8 +250,26 @@ StyleSheetPropertyAnimation::StyleSheetPropertyAnimation( const AnimationDefinit
 														  const AnimationOrigin& animationOrigin ) :
 	mAnimation( animation ),
 	mPropertyDef( propertyDef ),
-	mStates( states ),
-	mAnimationStepsTime( animationStepsTime ),
+	mStates( std::make_move_iterator( states.begin() ), std::make_move_iterator( states.end() ) ),
+	mAnimationStepsTime( std::make_move_iterator( animationStepsTime.begin() ),
+						 std::make_move_iterator( animationStepsTime.end() ) ),
+	mPendingIterations( animation.getIterations() ),
+	mPropertyIndex( propertyIndex ),
+	mAnimationOrigin( animationOrigin ),
+	mPaused( mAnimation.isPaused() ) {
+	mId = ID;
+}
+
+StyleSheetPropertyAnimation::StyleSheetPropertyAnimation( const AnimationDefinition& animation,
+														  const PropertyDefinition* propertyDef,
+														  SmallVector<std::string, 4> states,
+														  SmallVector<Float, 4> animationStepsTime,
+														  const Uint32& propertyIndex,
+														  const AnimationOrigin& animationOrigin ) :
+	mAnimation( animation ),
+	mPropertyDef( propertyDef ),
+	mStates( std::move( states ) ),
+	mAnimationStepsTime( std::move( animationStepsTime ) ),
 	mPendingIterations( animation.getIterations() ),
 	mPropertyIndex( propertyIndex ),
 	mAnimationOrigin( animationOrigin ),
@@ -321,15 +352,17 @@ Time StyleSheetPropertyAnimation::getTotalTime() {
 }
 
 Action* StyleSheetPropertyAnimation::clone() const {
-	return New( mAnimation, mPropertyDef, mStates, mAnimationStepsTime, mPropertyIndex,
-				mAnimationOrigin );
+	return eeNew( StyleSheetPropertyAnimation,
+				  ( mAnimation, mPropertyDef, mStates, mAnimationStepsTime, mPropertyIndex,
+					mAnimationOrigin ) );
 }
 
 Action* StyleSheetPropertyAnimation::reverse() const {
-	std::vector<std::string> vcopy( mStates );
+	SmallVector<std::string, 4> vcopy( mStates );
 	std::reverse( vcopy.begin(), vcopy.end() );
-	return New( mAnimation, mPropertyDef, vcopy, mAnimationStepsTime, mPropertyIndex,
-				mAnimationOrigin );
+	return eeNew( StyleSheetPropertyAnimation,
+				  ( mAnimation, mPropertyDef, std::move( vcopy ), mAnimationStepsTime,
+					mPropertyIndex, mAnimationOrigin ) );
 }
 
 const Uint32& StyleSheetPropertyAnimation::getPropertyIndex() const {
@@ -371,7 +404,8 @@ void StyleSheetPropertyAnimation::onUpdate( const Time& ) {
 			Float relativeProgress = curTime / relTime;
 			tweenProperty( widget, relativeProgress, mPropertyDef, mStates[curPos - 1],
 						   mStates[curPos], mAnimation.getTimingFunction(),
-						   mAnimation.getTimingFunctionParameters(), mPropertyIndex, isDone() );
+						   mAnimation.getTimingFunctionParametersInline(), mPropertyIndex,
+						   isDone() );
 		}
 	}
 }
@@ -480,16 +514,16 @@ void StyleSheetPropertyAnimation::prepareDirection() {
 }
 
 void StyleSheetPropertyAnimation::reverseAnimation() {
-	std::vector<std::string> reverseCopy( mStates );
+	SmallVector<std::string, 4> reverseCopy( mStates );
 	std::reverse( reverseCopy.begin(), reverseCopy.end() );
-	mStates = reverseCopy;
+	mStates = std::move( reverseCopy );
 
-	std::vector<Float> reverseTimes( mAnimationStepsTime );
+	SmallVector<Float, 4> reverseTimes( mAnimationStepsTime );
 	std::reverse( reverseTimes.begin(), reverseTimes.end() );
 	for ( size_t i = 0; i < reverseTimes.size(); i++ ) {
 		reverseTimes[i] = 1.f - reverseTimes[i];
 	}
-	mAnimationStepsTime = reverseTimes;
+	mAnimationStepsTime = std::move( reverseTimes );
 }
 
 }}} // namespace EE::UI::CSS
diff --git a/src/eepp/ui/css/timingfunction.cpp b/src/eepp/ui/css/timingfunction.cpp
index 2d74c1694..a8a98c7b6 100644
--- a/src/eepp/ui/css/timingfunction.cpp
+++ b/src/eepp/ui/css/timingfunction.cpp
@@ -1,29 +1,45 @@
-#include <eepp/system/functionstring.hpp>
+#include <eepp/core/string.hpp>
 #include <eepp/ui/css/timingfunction.hpp>
 
-using namespace EE::System;
-
 namespace EE { namespace UI { namespace CSS {
 
 TimingFunction TimingFunction::parse( std::string timingFunction ) {
-	String::trimInPlace( timingFunction );
-	String::toLowerInPlace( timingFunction );
-	if ( timingFunction.find_first_of( '(' ) == std::string::npos ) {
-		return { Ease::fromName( timingFunction ), {} };
-	} else {
-		TimingFunction tf;
-		FunctionString func( FunctionString::parse( timingFunction ) );
-		if ( !func.isEmpty() ) {
-			tf.interpolation = Ease::fromName( timingFunction, Ease::Interpolation::None );
-			const auto& params = func.getParameters();
-			for ( const auto& param : params ) {
-				double d;
-				if ( String::fromString( d, param ) )
-					tf.parameters.emplace_back( d );
-			}
-		}
-		return tf;
+	return parse( std::string_view{ timingFunction } );
+}
+
+TimingFunction TimingFunction::parse( std::string_view timingFunction ) {
+	timingFunction = String::trim( timingFunction, " \t\n\r\f\v" );
+	SmallVector<char, 64> normalized;
+	for ( char character : timingFunction )
+		normalized.emplace_back( character >= 'A' && character <= 'Z' ? character + 32
+																	  : character );
+	timingFunction = std::string_view{ normalized.data(), normalized.size() };
+
+	TimingFunction result;
+	const auto open = timingFunction.find( '(' );
+	if ( open == std::string_view::npos ) {
+		result.interpolation = Ease::fromName( timingFunction, Ease::Interpolation::None );
+		return result;
 	}
+	const auto close = timingFunction.rfind( ')' );
+	if ( close == std::string_view::npos || close <= open )
+		return result;
+	result.interpolation =
+		Ease::fromName( timingFunction.substr( 0, open ), Ease::Interpolation::None );
+
+	std::string_view parameters = timingFunction.substr( open + 1, close - open - 1 );
+	while ( !parameters.empty() && result.parameters.size() < 4 ) {
+		const auto comma = parameters.find( ',' );
+		std::string_view parameter = String::trim( parameters.substr( 0, comma ), " \t\n\r\f\v" );
+
+		double value = 0;
+		if ( String::fromString( value, parameter ) )
+			result.parameters.emplace_back( value );
+		if ( comma == std::string_view::npos )
+			break;
+		parameters.remove_prefix( comma + 1 );
+	}
+	return result;
 }
 
 }}} // namespace EE::UI::CSS
diff --git a/src/eepp/ui/css/transitiondefinition.cpp b/src/eepp/ui/css/transitiondefinition.cpp
index ff572b66b..64f3670f4 100644
--- a/src/eepp/ui/css/transitiondefinition.cpp
+++ b/src/eepp/ui/css/transitiondefinition.cpp
@@ -1,3 +1,4 @@
+#include <cctype>
 #include <eepp/core/string.hpp>
 #include <eepp/system/functionstring.hpp>
 #include <eepp/ui/css/propertydefinition.hpp>
@@ -6,122 +7,247 @@
 
 namespace EE { namespace UI { namespace CSS {
 
+namespace {
+
+template <typename Callback> void forEachCommaItem( std::string_view value, Callback&& callback ) {
+	System::FunctionString::forEachParameter( value, [&]( std::string_view item, bool ) {
+		callback( item );
+		return true;
+	} );
+}
+
+SmallVector<std::string_view, 4> splitTransitionTokens( std::string_view value ) {
+	SmallVector<std::string_view, 4> tokens;
+	std::size_t start = 0;
+	int parenthesisDepth = 0;
+	for ( std::size_t i = 0; i <= value.size(); ++i ) {
+		if ( i < value.size() ) {
+			if ( value[i] == '(' )
+				++parenthesisDepth;
+			else if ( value[i] == ')' && parenthesisDepth > 0 )
+				--parenthesisDepth;
+		}
+		if ( i == value.size() ||
+			 ( std::isspace( static_cast<unsigned char>( value[i] ) ) && parenthesisDepth == 0 ) ) {
+			if ( i > start )
+				tokens.emplace_back( value.substr( start, i - start ) );
+			while ( i + 1 < value.size() &&
+					std::isspace( static_cast<unsigned char>( value[i + 1] ) ) )
+				++i;
+			start = i + 1;
+		}
+	}
+	return tokens;
+}
+
+Time parseTime( std::string_view value ) {
+	value = String::trim( value, " \t\n\r\f\v" );
+	auto lower = []( char character ) {
+		return character >= 'A' && character <= 'Z' ? character + ( 'a' - 'A' ) : character;
+	};
+	bool milliseconds = value.size() >= 2 && lower( value[value.size() - 2] ) == 'm' &&
+						lower( value.back() ) == 's';
+	bool seconds = !milliseconds && !value.empty() && lower( value.back() ) == 's';
+	bool minutes = !milliseconds && !seconds && !value.empty() && lower( value.back() ) == 'm';
+	std::size_t numberLength = value.size() - ( milliseconds ? 2 : ( seconds || minutes ? 1 : 0 ) );
+	double number = 0;
+	const char* numberStart = value.data();
+	if ( numberLength > 0 && *numberStart == '+' ) {
+		++numberStart;
+		--numberLength;
+	}
+	if ( !String::fromString( number, std::string_view{ numberStart, numberLength } ) )
+		return Time::Zero;
+	if ( milliseconds )
+		return Milliseconds( number );
+	if ( minutes )
+		return Minutes( number );
+	return Seconds( number );
+}
+
+String::HashType lowerHash( std::string_view value ) {
+	return String::hashToLower( value.data(), static_cast<Int64>( value.size() ) );
+}
+
+std::string lowerString( std::string_view value ) {
+	std::string result{ value };
+	String::toLowerInPlace( result );
+	return result;
+}
+
+} // namespace
+
 UnorderedMap<std::string, TransitionDefinition> TransitionDefinition::parseTransitionProperties(
 	const std::vector<const StyleSheetProperty*>& styleSheetProperties ) {
-	std::vector<std::string> properties;
-	std::vector<Time> durations;
-	std::vector<Time> delays;
-	std::vector<Ease::Interpolation> timingFunctions;
-	std::vector<std::vector<double>> timingFunctionParameters;
+	SmallVector<std::string, 4> properties;
+	SmallVector<Time, 4> durations;
+	SmallVector<Time, 4> delays;
+	SmallVector<TimingFunction, 4> timingFunctions;
 	TransitionsMap transitions;
 
-	for ( auto& prop : styleSheetProperties ) {
-		if ( prop->getPropertyDefinition() == NULL )
+	for ( const StyleSheetProperty* property : styleSheetProperties ) {
+		if ( nullptr == property || nullptr == property->getPropertyDefinition() )
 			continue;
 
-		const PropertyDefinition* propDef = prop->getPropertyDefinition();
-
-		if ( propDef->getPropertyId() == PropertyId::Transition ) {
-			String::splitCb(
-				[&transitions, prop]( std::string_view str ) {
-					auto strTransition = String::trim( str );
-					auto splitTransition =
-						String::split( std::string{ strTransition }, " ", "", "()" );
-
-					if ( !splitTransition.empty() ) {
-						TransitionDefinition transitionDef;
-
-						if ( splitTransition.size() >= 2 ) {
-							std::string property = String::trim( splitTransition[0] );
-							String::toLowerInPlace( property );
-
-							Time duration =
-								StyleSheetProperty( prop->getName(),
-													String::toLower( splitTransition[1] ) )
-									.asTime();
-
-							transitionDef.property = property;
-							transitionDef.duration = duration;
-
-							if ( splitTransition.size() >= 3 ) {
-								TimingFunction tf( TimingFunction::parse( splitTransition[2] ) );
-								transitionDef.timingFunction = std::move( tf.interpolation );
-								transitionDef.timingFunctionParameters = std::move( tf.parameters );
-
-								if ( transitionDef.timingFunction == Ease::None &&
-									 splitTransition.size() == 3 ) {
-									transitionDef.delay =
-										StyleSheetProperty( prop->getName(),
-															String::toLower( splitTransition[2] ) )
-											.asTime();
-								} else if ( splitTransition.size() >= 4 ) {
-									transitionDef.delay =
-										StyleSheetProperty( prop->getName(),
-															String::toLower( splitTransition[3] ) )
-											.asTime();
-								}
-							}
-
-							transitions[transitionDef.getProperty()] = transitionDef;
-						}
+		switch ( property->getPropertyDefinition()->getPropertyId() ) {
+			case PropertyId::Transition:
+				forEachCommaItem( property->getValue(), [&]( std::string_view item ) {
+					auto tokens = splitTransitionTokens( item );
+					if ( tokens.size() < 2 )
+						return;
+					TransitionDefinition transition;
+					transition.property = lowerString( tokens[0] );
+					transition.duration = parseTime( tokens[1] );
+					if ( tokens.size() >= 3 ) {
+						TimingFunction timing = TimingFunction::parse( tokens[2] );
+						transition.timingFunction = timing.interpolation;
+						transition.timingFunctionParameters.assign( timing.parameters.begin(),
+																	timing.parameters.end() );
+						if ( transition.timingFunction == Ease::None && tokens.size() == 3 )
+							transition.delay = parseTime( tokens[2] );
+						else if ( tokens.size() >= 4 )
+							transition.delay = parseTime( tokens[3] );
 					}
-					return true;
-				},
-				prop->getValue(), ",", ",", "()" );
-		} else if ( propDef->getPropertyId() == PropertyId::TransitionDuration ) {
-			auto strDurations = String::split( prop->getValue(), ',' );
-
-			for ( auto dit = strDurations.begin(); dit != strDurations.end(); ++dit ) {
-				std::string duration( String::trim( *dit ) );
-				String::toLowerInPlace( duration );
-				durations.push_back( StyleSheetProperty( prop->getName(), duration ).asTime() );
-			}
-		} else if ( propDef->getPropertyId() == PropertyId::TransitionDelay ) {
-			auto strDelays = String::split( prop->getValue(), ',' );
-
-			for ( auto dit = strDelays.begin(); dit != strDelays.end(); ++dit ) {
-				std::string delay( String::trim( *dit ) );
-				String::toLowerInPlace( delay );
-				delays.push_back( StyleSheetProperty( prop->getName(), delay ).asTime() );
-			}
-		} else if ( propDef->getPropertyId() == PropertyId::TransitionTimingFunction ) {
-			auto strTimingFuncs = String::split( prop->getValue(), ",", "", "()" );
-
-			for ( auto dit = strTimingFuncs.begin(); dit != strTimingFuncs.end(); ++dit ) {
-				TimingFunction tf( TimingFunction::parse( *dit ) );
-				timingFunctions.emplace_back( tf.interpolation );
-				timingFunctionParameters.emplace_back( tf.parameters );
-			}
-		} else if ( propDef->getPropertyId() == PropertyId::TransitionProperty ) {
-			auto strProperties = String::split( prop->getValue(), ',' );
-
-			for ( auto dit = strProperties.begin(); dit != strProperties.end(); ++dit ) {
-				std::string property( String::trim( *dit ) );
-				String::toLowerInPlace( property );
-				properties.push_back( property );
-			}
+					transitions[transition.property] = std::move( transition );
+				} );
+				break;
+			case PropertyId::TransitionDuration:
+				forEachCommaItem( property->getValue(), [&]( std::string_view item ) {
+					durations.emplace_back( parseTime( item ) );
+				} );
+				break;
+			case PropertyId::TransitionDelay:
+				forEachCommaItem( property->getValue(), [&]( std::string_view item ) {
+					delays.emplace_back( parseTime( item ) );
+				} );
+				break;
+			case PropertyId::TransitionTimingFunction:
+				forEachCommaItem( property->getValue(), [&]( std::string_view item ) {
+					timingFunctions.emplace_back( TimingFunction::parse( item ) );
+				} );
+				break;
+			case PropertyId::TransitionProperty:
+				forEachCommaItem( property->getValue(), [&]( std::string_view item ) {
+					properties.emplace_back( lowerString( item ) );
+				} );
+				break;
+			default:
+				break;
 		}
 	}
 
-	for ( size_t i = 0; i < properties.size(); i++ ) {
-		const std::string& property = properties.at( i );
-		TransitionDefinition transitionDef;
-
-		transitionDef.property = property;
-
+	for ( std::size_t i = 0; i < properties.size(); ++i ) {
+		TransitionDefinition transition;
+		transition.property = properties[i];
 		if ( !durations.empty() )
-			transitionDef.duration = durations[i % durations.size()];
-
+			transition.duration = durations[i % durations.size()];
 		if ( !delays.empty() )
-			transitionDef.delay = delays[i % delays.size()];
-
+			transition.delay = delays[i % delays.size()];
 		if ( !timingFunctions.empty() ) {
-			size_t idx = !delays.empty() ? i % delays.size() : 0;
-			transitionDef.timingFunction = timingFunctions[idx];
-			transitionDef.timingFunctionParameters = timingFunctionParameters[idx];
+			const TimingFunction& timing = timingFunctions[i % timingFunctions.size()];
+			transition.timingFunction = timing.interpolation;
+			transition.timingFunctionParameters.assign( timing.parameters.begin(),
+														timing.parameters.end() );
 		}
+		transitions[transition.property] = std::move( transition );
+	}
 
-		transitions[property] = transitionDef;
+	return transitions;
+}
+
+void ComputedTransitions::set( const ComputedTransitionDefinition& transition ) {
+	for ( auto& current : mTransitions ) {
+		if ( current.propertyNameHash == transition.propertyNameHash ) {
+			current = transition;
+			return;
+		}
+	}
+	mTransitions.emplace_back( transition );
+}
+
+const ComputedTransitionDefinition*
+ComputedTransitions::get( String::HashType propertyNameHash ) const {
+	const ComputedTransitionDefinition* all = nullptr;
+	for ( const auto& transition : mTransitions ) {
+		if ( transition.propertyNameHash == propertyNameHash )
+			return &transition;
+		if ( transition.propertyNameHash == String::hash( "all" ) )
+			all = &transition;
+	}
+	return all;
+}
+
+ComputedTransitions
+ComputedTransitions::parse( const std::vector<const StyleSheetProperty*>& styleSheetProperties ) {
+	SmallVector<String::HashType, 4> properties;
+	SmallVector<Time, 4> durations;
+	SmallVector<Time, 4> delays;
+	SmallVector<TimingFunction, 4> timingFunctions;
+	ComputedTransitions transitions;
+
+	for ( const StyleSheetProperty* property : styleSheetProperties ) {
+		if ( nullptr == property || nullptr == property->getPropertyDefinition() )
+			continue;
+
+		switch ( property->getPropertyDefinition()->getPropertyId() ) {
+			case PropertyId::Transition:
+				forEachCommaItem( property->getValue(), [&]( std::string_view item ) {
+					auto tokens = splitTransitionTokens( item );
+					if ( tokens.size() < 2 )
+						return;
+					ComputedTransitionDefinition transition;
+					transition.propertyNameHash = lowerHash( tokens[0] );
+					transition.duration = parseTime( tokens[1] );
+					if ( tokens.size() >= 3 ) {
+						TimingFunction timing = TimingFunction::parse( tokens[2] );
+						transition.timingFunction = timing.interpolation;
+						transition.timingFunctionParameters = std::move( timing.parameters );
+						if ( transition.timingFunction == Ease::None && tokens.size() == 3 )
+							transition.delay = parseTime( tokens[2] );
+						else if ( tokens.size() >= 4 )
+							transition.delay = parseTime( tokens[3] );
+					}
+					transitions.set( transition );
+				} );
+				break;
+			case PropertyId::TransitionDuration:
+				forEachCommaItem( property->getValue(), [&]( std::string_view item ) {
+					durations.emplace_back( parseTime( item ) );
+				} );
+				break;
+			case PropertyId::TransitionDelay:
+				forEachCommaItem( property->getValue(), [&]( std::string_view item ) {
+					delays.emplace_back( parseTime( item ) );
+				} );
+				break;
+			case PropertyId::TransitionTimingFunction:
+				forEachCommaItem( property->getValue(), [&]( std::string_view item ) {
+					timingFunctions.emplace_back( TimingFunction::parse( item ) );
+				} );
+				break;
+			case PropertyId::TransitionProperty:
+				forEachCommaItem( property->getValue(), [&]( std::string_view item ) {
+					properties.emplace_back( lowerHash( item ) );
+				} );
+				break;
+			default:
+				break;
+		}
+	}
+
+	for ( std::size_t i = 0; i < properties.size(); ++i ) {
+		ComputedTransitionDefinition transition;
+		transition.propertyNameHash = properties[i];
+		if ( !durations.empty() )
+			transition.duration = durations[i % durations.size()];
+		if ( !delays.empty() )
+			transition.delay = delays[i % delays.size()];
+		if ( !timingFunctions.empty() ) {
+			const TimingFunction& timing = timingFunctions[i % timingFunctions.size()];
+			transition.timingFunction = timing.interpolation;
+			transition.timingFunctionParameters = timing.parameters;
+		}
+		transitions.set( transition );
 	}
 
 	return transitions;
diff --git a/src/eepp/ui/uihtmlwidget.cpp b/src/eepp/ui/uihtmlwidget.cpp
index a4652355d..630eada11 100644
--- a/src/eepp/ui/uihtmlwidget.cpp
+++ b/src/eepp/ui/uihtmlwidget.cpp
@@ -60,14 +60,7 @@ static bool hasDefiniteCSSHeight( UIWidget* widget ) {
 
 static CSSBaselineAlignValue parseBaselineAlign( UIHTMLWidget* widget,
 												 const StyleSheetProperty& property ) {
-	std::string_view val = property.value();
-	auto isSpace = []( char c ) {
-		return c == ' ' || c == '\t' || c == '\n' || c == '\r' || c == '\f';
-	};
-	while ( !val.empty() && isSpace( val.front() ) )
-		val.remove_prefix( 1 );
-	while ( !val.empty() && isSpace( val.back() ) )
-		val.remove_suffix( 1 );
+	std::string_view val = String::trim( std::string_view{ property.value() }, " \t\n\r\f\v" );
 	if ( val.empty() )
 		return {};
 
diff --git a/src/eepp/ui/uinodedrawable.cpp b/src/eepp/ui/uinodedrawable.cpp
index 5f3b5f7ce..0118c146c 100644
--- a/src/eepp/ui/uinodedrawable.cpp
+++ b/src/eepp/ui/uinodedrawable.cpp
@@ -1,3 +1,5 @@
+#include <array>
+#include <cctype>
 #include <eepp/core/core.hpp>
 #include <eepp/graphics/drawableresource.hpp>
 #include <eepp/graphics/image.hpp>
@@ -19,6 +21,36 @@ using namespace EE::Math::easing;
 
 namespace EE { namespace UI {
 
+namespace {
+
+struct WhitespaceParts {
+	std::array<std::string_view, 3> values;
+	std::size_t count{ 0 };
+
+	std::size_t size() const { return count; }
+	bool empty() const { return count == 0; }
+	std::string_view operator[]( std::size_t index ) const { return values[index]; }
+};
+
+WhitespaceParts splitWhitespace( std::string_view value ) {
+	WhitespaceParts parts;
+	std::size_t position = 0;
+	while ( position < value.size() && parts.count < parts.values.size() ) {
+		while ( position < value.size() &&
+				std::isspace( static_cast<unsigned char>( value[position] ) ) )
+			++position;
+		const std::size_t start = position;
+		while ( position < value.size() &&
+				!std::isspace( static_cast<unsigned char>( value[position] ) ) )
+			++position;
+		if ( position > start )
+			parts.values[parts.count++] = value.substr( start, position - start );
+	}
+	return parts;
+}
+
+} // namespace
+
 void UINodeDrawable::repeatFromText( const std::string& text, RepeatX& repeatX, RepeatY& repeatY ) {
 	auto parts = String::split( text, ' ' );
 
@@ -796,11 +828,9 @@ Sizef UINodeDrawable::LayerDrawable::calcDrawableSize( const std::string& drawab
 		Scale1 = eemax( Scale1, Scale2 );
 		size = Sizef( drawableSize.getWidth() * Scale1, drawableSize.getHeight() * Scale1 );
 	} else {
-		std::vector<std::string> sizePart = String::split( drawableSizeEq, ' ' );
-
-		if ( sizePart.size() == 1 ) {
-			sizePart.push_back( "auto" );
-		}
+		auto sizePart = splitWhitespace( drawableSizeEq );
+		if ( sizePart.size() == 1 )
+			sizePart.values[sizePart.count++] = "auto";
 
 		if ( sizePart.size() == 2 ) {
 			if ( sizePart[0] == "auto" && sizePart[1] == "auto" ) {
@@ -841,24 +871,22 @@ Sizef UINodeDrawable::LayerDrawable::calcDrawableSize( const std::string& drawab
 	return size;
 }
 
-Vector2f UINodeDrawable::LayerDrawable::calcPosition( std::string positionXEq,
-													  std::string positionYEq ) {
+Vector2f UINodeDrawable::LayerDrawable::calcPosition( const std::string& positionXEq,
+													  const std::string& positionYEq ) {
 	Vector2f position( Vector2f::Zero );
 
-	if ( positionXEq.empty() )
-		positionXEq = "center";
-
-	if ( positionYEq.empty() )
-		positionYEq = "center";
-
-	auto posX = String::split( positionXEq, ' ' );
-	auto posY = String::split( positionYEq, ' ' );
+	const std::string_view positionX =
+		positionXEq.empty() ? std::string_view{ "center" } : std::string_view{ positionXEq };
+	const std::string_view positionY =
+		positionYEq.empty() ? std::string_view{ "center" } : std::string_view{ positionYEq };
+	auto posX = splitWhitespace( positionX );
+	auto posY = splitWhitespace( positionY );
 
 	if ( posX.empty() || posY.empty() )
 		return position;
 
-	bool needsRoundingX = positionXEq.back() == '%';
-	bool needsRoundingY = positionYEq.back() == '%';
+	bool needsRoundingX = positionX.back() == '%';
+	bool needsRoundingY = positionY.back() == '%';
 
 	Sizef ownerSize = mContainer->getOwner()->getPixelsSize();
 	Float refWidth = ownerSize.getWidth();
diff --git a/src/eepp/ui/uistyle.cpp b/src/eepp/ui/uistyle.cpp
index 38d13de1e..a2a7f01f7 100644
--- a/src/eepp/ui/uistyle.cpp
+++ b/src/eepp/ui/uistyle.cpp
@@ -135,8 +135,8 @@ void UIStyle::setStyleSheetProperties( const CSS::StyleSheetProperties& properti
 }
 
 bool UIStyle::hasTransition( const std::string& propertyName ) {
-	return mTransitions.find( propertyName ) != mTransitions.end() ||
-		   mTransitions.find( "all" ) != mTransitions.end();
+	return mDefinition && mDefinition->getTransitions().get( String::hashToLower(
+							  propertyName.c_str(), static_cast<Int64>( propertyName.size() ) ) );
 }
 
 StyleSheetPropertyAnimation* UIStyle::getAnimation( const PropertyDefinition* propertyDef ) {
@@ -160,15 +160,20 @@ bool UIStyle::hasAnimation( const PropertyDefinition* propertyDef ) {
 }
 
 TransitionDefinition UIStyle::getTransition( const std::string& propertyName ) {
-	auto propertyTransitionIt = mTransitions.find( propertyName );
-
-	if ( propertyTransitionIt != mTransitions.end() ) {
-		return propertyTransitionIt->second;
-	} else if ( ( propertyTransitionIt = mTransitions.find( "all" ) ) != mTransitions.end() ) {
-		return propertyTransitionIt->second;
-	}
-
-	return TransitionDefinition();
+	TransitionDefinition transition;
+	if ( !mDefinition )
+		return transition;
+	const auto* computed = mDefinition->getTransitions().get(
+		String::hashToLower( propertyName.c_str(), static_cast<Int64>( propertyName.size() ) ) );
+	if ( !computed )
+		return transition;
+	transition.property = propertyName;
+	transition.timingFunction = computed->timingFunction;
+	transition.timingFunctionParameters.assign( computed->timingFunctionParameters.begin(),
+												computed->timingFunctionParameters.end() );
+	transition.delay = computed->delay;
+	transition.duration = computed->duration;
+	return transition;
 }
 
 const bool& UIStyle::isChangingState() const {
@@ -339,9 +344,9 @@ void UIStyle::setVariableFromValue( StyleSheetProperty* property, const std::str
 	for ( int depth = 0; depth < maxDepth; depth++ ) {
 		bool changed = false;
 		if ( !property->getVarCache().empty() ) {
-			auto varCacheCopy = property->getVarCache();
-			for ( auto& var : varCacheCopy ) {
-				for ( auto& val : var.variableList ) {
+			const auto& varCache = property->getVarCache();
+			for ( const auto& var : varCache ) {
+				for ( const auto& val : var.variableList ) {
 					StyleSheetVariable variable( getVariable( val ) );
 					if ( !variable.isEmpty() ) {
 						String::replaceAll( newValue, var.definition, variable.getValue() );
@@ -432,11 +437,6 @@ void UIStyle::onStateChange() {
 
 		mWidget->beginAttributesTransaction();
 
-		if ( nullptr != mDefinition && !mDefinition->getTransitionProperties().empty() ) {
-			mTransitions = TransitionDefinition::parseTransitionProperties(
-				mDefinition->getTransitionProperties() );
-		}
-
 		for ( PropertyId prop : changedProperties ) {
 			std::optional<StyleSheetProperty> resolvedProperty;
 			StyleSheetProperty* property = getResolvedLocalProperty( prop, resolvedProperty );
@@ -669,11 +669,17 @@ void UIStyle::applyStyleSheetProperty( const StyleSheetProperty& originalPropert
 				}
 			}
 
-			TransitionDefinition transitionInfo( getTransition( property->getName() ) );
+			const ComputedTransitionDefinition* transitionInfo =
+				mDefinition ? mDefinition->getTransitions().get( propertyDefinition->getId() )
+							: nullptr;
+			if ( nullptr == transitionInfo ) {
+				mWidget->applyProperty( *property );
+				return;
+			}
 
-			std::vector<Action*> previousTransitions =
-				mWidget->getActionsByTag( propertyDefinition->getId() );
-			std::vector<Action*> removeTransitions;
+			SmallVector<Action*, 4> previousTransitions;
+			mWidget->getActionsByTag( propertyDefinition->getId(), previousTransitions );
+			SmallVector<Action*, 4> removeTransitions;
 			StyleSheetPropertyAnimation* prevTransition = NULL;
 
 			if ( !previousTransitions.empty() ) {
@@ -707,9 +713,9 @@ void UIStyle::applyStyleSheetProperty( const StyleSheetProperty& originalPropert
 					currentProgress = eemin( 1.f, currentProgress );
 					if ( 0.f != currentProgress ) {
 						elapsed = Milliseconds( ( 1.f - currentProgress ) *
-												transitionInfo.getDuration().asMilliseconds() );
+												transitionInfo->duration.asMilliseconds() );
 					} else {
-						elapsed = transitionInfo.getDuration();
+						elapsed = transitionInfo->duration;
 					}
 					startValue = prevTransition->getEndValue();
 				} else if ( startValue == prevTransition->getEndValue() ) {
@@ -723,9 +729,8 @@ void UIStyle::applyStyleSheetProperty( const StyleSheetProperty& originalPropert
 
 			StyleSheetPropertyAnimation* newTransition = StyleSheetPropertyAnimation::New(
 				propertyDefinition, startValue, property->getValue(), property->getIndex(),
-				transitionInfo.getDuration(), transitionInfo.getDelay(),
-				transitionInfo.getTimingFunction(), transitionInfo.getTimingFunctionParameters(),
-				AnimationOrigin::Transition );
+				transitionInfo->duration, transitionInfo->delay, transitionInfo->timingFunction,
+				transitionInfo->timingFunctionParameters, AnimationOrigin::Transition );
 			newTransition->setElapsed( elapsed );
 			newTransition->setTag( propertyDefinition->getId() );
 			mWidget->runAction( newTransition );
diff --git a/src/tests/unit_tests/action_transition_tests.cpp b/src/tests/unit_tests/action_transition_tests.cpp
new file mode 100644
index 000000000..4624f56a3
--- /dev/null
+++ b/src/tests/unit_tests/action_transition_tests.cpp
@@ -0,0 +1,125 @@
+#include "utest.h"
+#include <eepp/scene/actions/delay.hpp>
+#include <eepp/scene/actions/runnable.hpp>
+#include <eepp/ui/css/stylesheetspecification.hpp>
+#include <eepp/ui/css/transitiondefinition.hpp>
+
+using namespace EE;
+using namespace EE::Math;
+using namespace EE::Scene;
+using namespace EE::Scene::Actions;
+using namespace EE::System;
+using namespace EE::UI::CSS;
+
+UTEST( ActionPool, reusesCompletedActionSlots ) {
+	Delay* first = Delay::New( Milliseconds( 1 ) );
+	void* firstAddress = first;
+	eeDelete( first );
+
+	Delay* second = Delay::New( Milliseconds( 2 ) );
+	EXPECT_EQ( static_cast<void*>( second ), firstAddress );
+	eeDelete( second );
+}
+
+UTEST( ActionCallbacks, listenerMutationUsesEventSnapshot ) {
+	Delay* action = Delay::New( Time::Zero );
+	int callbackCount = 0;
+	Uint32 firstCallback = 0;
+	Uint32 secondCallback = 0;
+	firstCallback = action->addEventListener( Action::OnStart, [&]( Action* sender, const auto& ) {
+		++callbackCount;
+		sender->removeEventListener( secondCallback );
+	} );
+	secondCallback = action->addEventListener( Action::OnStart, [&]( Action* sender, const auto& ) {
+		++callbackCount;
+		sender->removeEventListener( firstCallback );
+	} );
+
+	action->start();
+	EXPECT_EQ( callbackCount, 2 );
+	eeDelete( action );
+}
+
+UTEST( Transitions, compactShorthandParsesWithoutLosingSemantics ) {
+	auto* specification = StyleSheetSpecification::instance();
+	StyleSheetProperty shorthand(
+		specification->getProperty( PropertyId::Transition ),
+		"opacity 150ms cubic-bezier(0.1, 0.2, 0.3, 0.4) 25ms, width 2s linear" );
+	std::vector<const StyleSheetProperty*> properties{ &shorthand };
+
+	ComputedTransitions transitions = ComputedTransitions::parse( properties );
+	const auto* opacity = transitions.get( String::hash( "opacity" ) );
+	const auto* width = transitions.get( String::hash( "width" ) );
+	ASSERT_TRUE( nullptr != opacity );
+	ASSERT_TRUE( nullptr != width );
+	EXPECT_EQ( opacity->duration.asMilliseconds(), 150.0 );
+	EXPECT_EQ( opacity->delay.asMilliseconds(), 25.0 );
+	EXPECT_TRUE( opacity->timingFunction == Ease::CubizBezier );
+	ASSERT_EQ( opacity->timingFunctionParameters.size(), 4u );
+	EXPECT_EQ( opacity->timingFunctionParameters[2], 0.3 );
+	EXPECT_EQ( width->duration.asSeconds(), 2.0 );
+	EXPECT_TRUE( width->timingFunction == Ease::Linear );
+}
+
+UTEST( Transitions, longhandListsCycleIndependently ) {
+	auto* specification = StyleSheetSpecification::instance();
+	StyleSheetProperty property( specification->getProperty( PropertyId::TransitionProperty ),
+								 "opacity,width,height" );
+	StyleSheetProperty duration( specification->getProperty( PropertyId::TransitionDuration ),
+								 "1s,2s" );
+	StyleSheetProperty delay( specification->getProperty( PropertyId::TransitionDelay ),
+							  "10ms,20ms" );
+	StyleSheetProperty timing( specification->getProperty( PropertyId::TransitionTimingFunction ),
+							   "linear,quadratic-in,bounce-out" );
+	std::vector<const StyleSheetProperty*> properties{ &property, &duration, &delay, &timing };
+
+	ComputedTransitions transitions = ComputedTransitions::parse( properties );
+	const auto* opacity = transitions.get( String::hash( "opacity" ) );
+	const auto* width = transitions.get( String::hash( "width" ) );
+	const auto* height = transitions.get( String::hash( "height" ) );
+	ASSERT_TRUE( nullptr != opacity );
+	ASSERT_TRUE( nullptr != width );
+	ASSERT_TRUE( nullptr != height );
+	EXPECT_EQ( opacity->duration.asSeconds(), 1.0 );
+	EXPECT_EQ( width->duration.asSeconds(), 2.0 );
+	EXPECT_EQ( height->duration.asSeconds(), 1.0 );
+	EXPECT_EQ( height->delay.asMilliseconds(), 10.0 );
+	EXPECT_TRUE( opacity->timingFunction == Ease::Linear );
+	EXPECT_TRUE( width->timingFunction == Ease::QuadraticIn );
+	EXPECT_TRUE( height->timingFunction == Ease::BounceOut );
+
+	TransitionsMap compatibility = TransitionDefinition::parseTransitionProperties( properties );
+	EXPECT_TRUE( compatibility["height"].getTimingFunction() == Ease::BounceOut );
+}
+
+UTEST( Transitions, allIsFallbackAndSpecificPropertyWins ) {
+	auto* specification = StyleSheetSpecification::instance();
+	StyleSheetProperty shorthand( specification->getProperty( PropertyId::Transition ),
+								  "all 1s linear, opacity 2s sine-in" );
+	std::vector<const StyleSheetProperty*> properties{ &shorthand };
+	ComputedTransitions transitions = ComputedTransitions::parse( properties );
+
+	const auto* width = transitions.get( String::hash( "width" ) );
+	const auto* opacity = transitions.get( String::hash( "opacity" ) );
+	ASSERT_TRUE( nullptr != width );
+	ASSERT_TRUE( nullptr != opacity );
+	EXPECT_EQ( width->duration.asSeconds(), 1.0 );
+	EXPECT_EQ( opacity->duration.asSeconds(), 2.0 );
+	EXPECT_TRUE( opacity->timingFunction == Ease::SineIn );
+}
+
+UTEST( Transitions, allocationLightParserPreservesAcceptedSpelling ) {
+	auto* specification = StyleSheetSpecification::instance();
+	StyleSheetProperty shorthand( specification->getProperty( PropertyId::Transition ),
+								  "opacity +150MS CUBIC-BEZIER(0.1, 0.2, 0.3, 0.4) +25MS" );
+	std::vector<const StyleSheetProperty*> properties{ &shorthand };
+
+	ComputedTransitions transitions = ComputedTransitions::parse( properties );
+	const auto* opacity = transitions.get( String::hash( "opacity" ) );
+	ASSERT_TRUE( nullptr != opacity );
+	EXPECT_EQ( opacity->duration.asMilliseconds(), 150.0 );
+	EXPECT_EQ( opacity->delay.asMilliseconds(), 25.0 );
+	EXPECT_TRUE( opacity->timingFunction == Ease::CubizBezier );
+	EXPECT_EQ( opacity->timingFunctionParameters.size(), 4u );
+	EXPECT_TRUE( TimingFunction::parse( "cubic-bezier(" ).interpolation == Ease::None );
+}
diff --git a/src/tests/unit_tests/functionstring_tests.cpp b/src/tests/unit_tests/functionstring_tests.cpp
index 437243218..a1a5c2270 100644
--- a/src/tests/unit_tests/functionstring_tests.cpp
+++ b/src/tests/unit_tests/functionstring_tests.cpp
@@ -60,3 +60,44 @@ UTEST( FunctionString, functionString ) {
 	testCase( R"(test30("str'ing", 'str"ing2'))", "test30", { "str'ing", "str\"ing2" } );
 	testCase( R"(test31('', ''))", "test31", { "", "" } );
 }
+
+UTEST( FunctionString, nonOwningViewParser ) {
+	constexpr std::string_view input =
+		R"(  compose  ( first, nested(1, "two,three"), 'quoted, value', "escaped\"quote", '' ) )";
+	auto function = FunctionString::parseView( input );
+	EXPECT_FALSE( function.isEmpty() );
+	EXPECT_TRUE( "compose"sv == function.getName() );
+
+	SmallVector<std::string_view, 5> parameters;
+	SmallVector<bool, 5> strings;
+	EXPECT_TRUE( function.forEachParameter( [&]( std::string_view parameter, bool wasString ) {
+		parameters.emplace_back( parameter );
+		strings.emplace_back( wasString );
+		return true;
+	} ) );
+
+	EXPECT_EQ( 5u, parameters.size() );
+	EXPECT_TRUE( "first"sv == parameters[0] );
+	EXPECT_TRUE( R"(nested(1, "two,three"))"sv == parameters[1] );
+	EXPECT_TRUE( "quoted, value"sv == parameters[2] );
+	EXPECT_TRUE( R"(escaped\"quote)"sv == parameters[3] );
+	EXPECT_TRUE( ""sv == parameters[4] );
+	EXPECT_FALSE( strings[0] );
+	EXPECT_FALSE( strings[1] );
+	EXPECT_TRUE( strings[2] );
+	EXPECT_TRUE( strings[3] );
+	EXPECT_TRUE( strings[4] );
+}
+
+UTEST( FunctionString, nonOwningViewParserCanStopEarly ) {
+	auto function = FunctionString::parseView( "fn(one, two, three)"sv );
+	int calls = 0;
+	std::string_view firstParameter;
+	EXPECT_FALSE( function.forEachParameter( [&]( std::string_view parameter, bool ) {
+		++calls;
+		firstParameter = parameter;
+		return false;
+	} ) );
+	EXPECT_EQ( 1, calls );
+	EXPECT_TRUE( "one"sv == firstParameter );
+}