When clicking on the 'edit' next to each thread in the threads list, it makes an ajax call and creates the html interface to edit that thread. But it does that on each click, instead keeping it in cache.
It's also creates a new menu for prefixes on each click.
It's not exactly a bug, but it's the only place which works like that (that I'm aware of).
This all created by repeatedly clicking on a single edit link
There are multiple places that do not cache their results, specifically when we want to handle the case where values may have changed. This is sort of one of those cases, but it's also simply not caching as we're making a POST request.