From what I can tell, this game is just really resource hungry. My iPad Air can barely run this game now a days. That's a bit frustrating considering it's not that old of a device. I think it may have to do with their game engine.
I've been saying this before, but I think they need make their game engine more efficient. This isn't a live action game for it to be this glitchy. My frame rates are just awful, and visiting friends is nearly impossible because of all the crashes.
All I can say is, this game isn't friendly towards heavy city designers. Considering that the game is only going to get bigger, I see more frame rate issues, especially during events. But let's see what happens. Maybe they'll fix that soon.