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
/**
	 * Default constructor.
	 */
	public JavaEditor() {
		super();
	}
	
	/*
	 * @see org.eclipse.ui.texteditor.AbstractDecoratedTextEditor#initializeKeyBindingScopes()
	 */
	protected void initializeKeyBindingScopes() {
		setKeyBindingScopes(new String[] { "org.eclipse.jdt.ui.javaEditorScope" });  
	}
	
	/*
	 * @see org.eclipse.ui.texteditor.AbstractDecoratedTextEditor#initializeEditor()
	 */
	protected void initializeEditor() {
		IPreferenceStore store= createCombinedPreferenceStore(null);
		setPreferenceStore(store);
		JavaTextTools textTools= JavaPlugin.getDefault().getJavaTextTools();
		setSourceViewerConfiguration(new JavaSourceViewerConfiguration(textTools.getColorManager(), store, this, IJavaPartitions.JAVA_PARTITIONING));
		fMarkOccurrenceAnnotations= store.getBoolean(PreferenceConstants.EDITOR_MARK_OCCURRENCES);
		fStickyOccurrenceAnnotations= store.getBoolean(PreferenceConstants.EDITOR_STICKY_OCCURRENCES);
		fMarkTypeOccurrences= store.getBoolean(PreferenceConstants.EDITOR_MARK_TYPE_OCCURRENCES);
		fMarkMethodOccurrences= store.getBoolean(PreferenceConstants.EDITOR_MARK_METHOD_OCCURRENCES);
		fMarkConstantOccurrences= store.getBoolean(PreferenceConstants.EDITOR_MARK_CONSTANT_OCCURRENCES);
		fMarkFieldOccurrences= store.getBoolean(PreferenceConstants.EDITOR_MARK_FIELD_OCCURRENCES);
		fMarkLocalVariableypeOccurrences= store.getBoolean(PreferenceConstants.EDITOR_MARK_LOCAL_VARIABLE_OCCURRENCES);