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
internalRefreshAll(updateLabels);
			else{
				internalVirtualRefreshAll();
			}
		} else {
			Widget w = findItem(element);
			if (w != null) {
				updateItem(w, element);
			}
		}
	}
	/**
	 * Refresh all with virtual elements.
	 * 
	 * @since 3.1
	 */
	private void internalVirtualRefreshAll() {
		
		Object root = getRoot();
		IContentProvider contentProvider = getContentProvider();
		
		
		if(!(contentProvider instanceof ILazyContentProvider) 
				&& (contentProvider instanceof IStructuredContentProvider)) {
			
			if(root != null)
				virtualManager.cachedElements = 
					((IStructuredContentProvider) getContentProvider()).getElements(root);
		}
		getTable().clearAll();