My game keeps freezing when I try to get armor

[Teaganzane]

So I keep on doing a bunch of different maps on survival cause I've been told its a great way to good the best gear, and EVERYTIME I get anywhere close to wave 30's my game crashes so I dont really get any good gear, if you have any ideas or could help me out with this I would appreciate it very much! Im just trying to get good gear! :p