My game has been sluggish lately so I looked into my storage and behold! CS was taking up over 9GB. I checked my iPad and my game there is only taking up just over 250MB. I do play a lot more on my phone, but a there's no reason for the game to take up that much storage.
I deleted and reinstalled the game on my phone. It took a while to repopulate my kingdom but now it's only taking up under 200MB. If your game is acting up a lot with a lot of freezes or sudden shutdowns maybe you can also try deleting and reinstalling.
I wonder if this is something S8 can look into for us?