Bug 19275 editor: context menu slow on large files
F2 it's slow, but only the first time after a change. then it's fast afain you make another change - it's slow again
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/compare/JavaHistoryAction.java
/**
	 * Implements the IStreamContentAccessor and ITypedElement protocols
	 * for a TextBuffer.
	 */
	class JavaTextBufferNode implements ITypedElement, IStreamContentAccessor {
		
		private TextBuffer fBuffer;