Bug 81983 [preferences] Disabling and enabling folding on small file takes forever
3.1 M4 Using enable/disable folding on a small CU takes forever. This is caused by the recent change to apply the preference to all Java editors. In another (hidden) window (Debug) I had StyledText open which (understandably) took long to react on the preference change. Non-visible editor's should not react to this change until they become visible.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/javaeditor/JavaEditor.java
}
	}
	
	protected void uninstallOccurrencesFinder() {
		fMarkOccurrenceAnnotations= false;
		
		if (fOccurrencesFinderJob != null) {
			fOccurrencesFinderJob.cancel();
			fOccurrencesFinderJob= null;
		}
		if (fOccurrencesFinderJobCanceler != null) {
			fOccurrencesFinderJobCanceler.uninstall();
			fOccurrencesFinderJobCanceler= null;
		}
		
		if (fPostSelectionListenerWithAST != null) {
			SelectionListenerWithASTManager.getDefault().removeListener(this, fPostSelectionListenerWithAST);
			fPostSelectionListenerWithAST= null;
		}
		
		removeOccurrenceAnnotations();
	}
	
	protected boolean isMarkingOccurrences() {
		return fMarkOccurrenceAnnotations;
	}
	
	boolean markOccurrencesOfType(IBinding binding) {
		
		if (binding == null)