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
IPartService service= window.getPartService();
		IWorkbenchPart part= service.getActivePart();
		return part;
	}
	
	/*
	 * @see StatusTextEditor#getStatusHeader(IStatus)
	 */
	protected String getStatusHeader(IStatus status) {
		if (fEncodingSupport != null) {
			String message= fEncodingSupport.getStatusHeader(status);
			if (message != null)
				return message;
		}
		return super.getStatusHeader(status);
	}
	
	/*
	 * @see StatusTextEditor#getStatusBanner(IStatus)
	 */
	protected String getStatusBanner(IStatus status) {
		if (fEncodingSupport != null) {
			String message= fEncodingSupport.getStatusBanner(status);
			if (message != null)
				return message;
		}
		return super.getStatusBanner(status);
	}
	
	/*