There is a thread here where you can check if your device is supported and also go through some troubleshooting steps: https://care.king.com/en/candy-crush-saga/loading-crashing-issues-ios I started playing candy crush saga after I got this iPad over two years ago. Everything worked fine up until a couple months ago
I think it's all tied in together, Facebook,candy crush and messenger. Facebook will go blank for no reason also, and messenger will just pop up on its own. All three together and not worth a hill of beans.