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
return;
		synchronized (getLockObject(annotationModel)) {
			if (annotationModel instanceof IAnnotationModelExtension) {
				((IAnnotationModelExtension)annotationModel).replaceAnnotations(fOccurrenceAnnotations, null);
			} else {
				for (int i= 0, length= fOccurrenceAnnotations.length; i < length; i++)
					annotationModel.removeAnnotation(fOccurrenceAnnotations[i]);
			}
			fOccurrenceAnnotations= null;
		}
	}
	protected void uninstallOverrideIndicator() {
		if (fOverrideIndicatorManager != null) {
			fOverrideIndicatorManager.removeAnnotations();
			fOverrideIndicatorManager= null;
		}
	}
	protected void installOverrideIndicator(boolean provideAST) {
		uninstallOverrideIndicator();
		IAnnotationModel model= getDocumentProvider().getAnnotationModel(getEditorInput());
		final IJavaElement inputElement= getInputJavaElement();
		if (model == null || inputElement == null)
			return;
		fOverrideIndicatorManager= new OverrideIndicatorManager(model, inputElement, null);
		
		if (provideAST) {
			Job job= new Job(JavaEditorMessages.getString("OverrideIndicatorManager.intallJob")) { 
				/*
				 * @see org.eclipse.core.runtime.jobs.Job#run(org.eclipse.core.runtime.IProgressMonitor)
				 * @since 3.0