Freezing or very slow on iPad after app is inactive for awhile

I just wanted to tell you guys about a bug I keep getting on my iPad. So If I have minecraft open and then I leave the app and don't go on it for a little while, ten when I go back on minecraft goes frozen for a few minutes and when I finally get back to my home screen it runs at about 1 frame every 2 seconds for up to 30 seconds. It's really annoying. This happens even if I have saved and exited the world, too. The only way to stop it from happening is clearing the app.