Bug 89971 [Viewers] Viewers that use IViewerLabelProvider do too many instanceof checks
M6 Checking our viewer the calls to buildLabel are doing too many instanceof checks. As a result certain viewers (such as the table viewer) are twice as slow as they were in 3.0 due to these checks. I have written some performance suites to test the Table, Tree, List and Combo viewers. Table and Tree have this issue.
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/TableViewer.java
* @since 3.1
	 */
	private void createItem(Object element, int index) {
		if(virtualManager == null)
			updateItem(new TableItem(getTable(), SWT.NONE, index), element);
		else{
			virtualManager.notVisibleAdded(element,index);
			
		}
	}
	/**
	 * Adds the given element to this table viewer. If this viewer does not have
	 * a sorter, the element is added at the end; otherwise the element is
	 * inserted at the appropriate position.
	 * <p>
	 * This method should be called (by the content provider) when a single
	 * element has been added to the model, in order to cause the viewer to
	 * accurately reflect the model. This method only affects the viewer, not
	 * the model. Note that there is another method for efficiently processing
	 * the simultaneous addition of multiple elements.
	 * </p>
	 * 
	 * @param element
	 *            the element to add
	 */
	public void add(Object element) {
		add(new Object[] { element });
	}
	/**
	 * Cancels a currently active cell editor. All changes already done in the