Dont' compute decorators and font-effects. Their computed values are as specified. Benchmark later to see what gives best performance.

Include/Rocket/Core/ComputedValues.h

@@ -199,8 +199,7 @@ struct ComputedValues
 	TransitionList transition;
 	AnimationList animation;
 
-	String decorator;
-	String font_effect;
+	// Decorators and font-effects are not computed, retrieve from local property
 };
 }
 

Source/Core/ElementStyle.cpp

@@ -939,11 +939,10 @@ DirtyPropertyList ElementStyle::ComputeValues(Style::ComputedValues& values, con
 			values.animation = p->Get<AnimationList>();
 			break;
 
+		// Decorators and font-effects are not computed, they are specified as they are given.
 		case PropertyId::Decorator:
-			values.decorator = p->Get<String>();
 			break;
 		case PropertyId::FontEffect:
-			values.font_effect = p->Get<String>();
 			break;
 		}
 	}