I don't remember ever seeing a checkbox like that. That would be a good idea - I think.

I suppose that I could test this by adding a playlist with only a few items on it that weren't previously on the player and then deleting it. If those tracks are deleted too, then maybe that's the culprit (it appears to hang when really it is resolving which files are orphaned and which are associated with other playlists).

Or maybe this is just a random bug.