Hello,
I have sent an email of this issue to support but thought to also include here and see if I can find an answer or at least anyone else with similar issues. I play mostly on my iPad 4th generation tablet and these issues relate to it.
So mid game my app will get laggy like it is struggling to keep up with receiving packets and then it will just close. This happens often and obviously makes the game difficult to play. If I chat in the team room while playing, or even just take a look around in messages or settings etc, I can expect a crash with the app closing even more promptly