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
internalDoSetInput(input);
	}
	
	private void internalDoSetInput(IEditorInput input) throws CoreException {
		super.doSetInput(input);
		
		if (getSourceViewer() instanceof JavaSourceViewer) {
			JavaSourceViewer viewer= (JavaSourceViewer)getSourceViewer();
			if (viewer.getReconciler() == null) {
				IReconciler reconciler= getSourceViewerConfiguration().getReconciler(viewer);
				if (reconciler != null) {
					reconciler.install(viewer);
					viewer.setReconciler(reconciler);
				}
			}
		}
		
		if (fEncodingSupport != null)
			fEncodingSupport.reset();
		
		setOutlinePageInput(fOutlinePage, input);
				
		if (fProjectionModelUpdater != null)
			fProjectionModelUpdater.initialize();
		
		if (isShowingOverrideIndicators())
			installOverrideIndicator(false);
	}
	/*