The sort function is glitchy when sorting an expanded hierarchical tree layout. To reproduce, go to the demo site and select a page that has a tree structure (like Actions->Outlinks). Then expand all the entries in the tree. Then click on one of the column headers to sort. You will see that it sorts (or at least re-renders) once for each branch of the tree that was expanded. I can reproduce this consistently on Firefox.
(In ) fixes #3027 prevent binding multiple click events for sorting data