Android is a garbage, even the kernel its from Linux, but with all Google spy and data stealing programs its not surprise that Android restart or crash so many times
Smartphones need alternatives like Cyanogen mod, sadly the support its no longer exist
joiplay does handle most of the games but yea, performance issues when it comes to rpgmv/mz games. not much on VX Ace ones, renpy ones are usually fine. some games do perform very nice even though they're heavy link mind luda meanwhile games like a struggle with sin really is struggling. it comes down to the dev too i guess.