Lagging and crashing

This has been happening since I first got it but the Minecraft app has been crashing and lagging and even with the latest update, which was 9/20/17 it still lags and crashes while the update has helped a lot, it hasn't completely fixed the issue and I know for a fact it's not the iPad I'm using as it is working just fine and is up to date. I would find it very helpful if I could at least get Mojang's email address.