I admit I was little sleep deprived when I was reading your post so I accept I misunderstood the main issue.
The game is fairly broken, in all ways that you mentioned and then some, depending on far you 'progress' with developing your dungeon. Even without the bugs, most combat skill this game expects you to utilize just doesn't really work/matter past a certain point anyway, so all the stuff I mentioned just feels like abusing something the developer forgot about / hasn't fixed yet.
Attacks seem to take a lot of processing power, and this has crashed my game at least twice when the enemies can start hitting with a flurry of 20 attacks in one turn as if the first hit isn't already a TKO. I don't know exactly if this is related to your issue, but them doing a stupid amount of moves against you at higher levels is 'normal' so it could at least explain why it's freezing.
Sorry if my post came off as offensive, I would have also preferred it if this game works as intended without the bugs or broken scaling issues it has.