Bug 38782 TreeViewer add calls a refresh
Our implementation of TreeViewer.add is naive and can all a refresh of the entire tree. It should be more like TableViewer.
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/AbstractTreeViewer.java
boolean addDummy = false;
		Object data = item.getData();
		if (data != null && equals(element, data)) {
			
			if (hasPlus != needsPlus) {
				if (needsPlus)
					addDummy = true;
				else
					removeAll = true;
			}
		} else {
			
			removeAll = true;
			addDummy = needsPlus;
			
			setExpanded(item, false);
		}
		if (removeAll) {
			
			Item[] items = getItems(item);
			for (int i = 0; i < items.length; i++) {
				if (items[i].getData() != null)
					disassociate(items[i]);
				items[i].dispose();
			}
		}
		if (addDummy)
			newItem(item, SWT.NULL, -1); 
	}
	/**