There are some new bug reports (and some old complaints) that I'll try to fix before Saturday. There are probably some new script problems that arose after I changed the assets folder system for modability.
Also there are some slowdown and crashing issues on some computers. The low FPS and crashing problems are unrelated, but I'll work on both of them.
EDIT: The game will crash on some computers if you load too many maps (and hence images) in one play session without quitting. So the temporary solution is to quit and reopen the game after you save to prevent crashes. Most computers don't have this problem, but I'll try to fix it in the next patch (or the one after).