Collapse/Uncollapse is slow with a large list of items

I have a list of about 600 objects that I'm displaying with TreeViews, and things are really slow when I collapse/uncollapse a single item. My code is basically the same as the controlled example, so I think the problem is that the re-render call after I toggle the collapsed state for one of the objects results in a re-render of EVERYTHING in the list of objects.

I've taken care to ensure that the has a unique key and that the child