Games crashing and freezing on lolipop 5.1

Hi all. So I recently bought ESTAR Beauty HD Quad Core Tablet for my kids, I know its not the best choice but couldn't afford more. It runs on Lolipop 5.1 android and the problem is with games and apps for Google Play, preinstalled games run perfectly like angry birds 2 or hill climb, but aby other game I install for them either freeze or crash with no error. I did all I can find to speed it up but no help. Not sure why it happens but can't fix it. Pls, help I really can't buy them a new one. Tnx

Welcome to Android Central! Did the tablet come with the Play Store, or did you have to install it yourself?

Whit Google Pay Store.

My guess is a firmware bug. In the future, avoid these cheap no-name or off-brand Android devices -- they're not worth it, even for how cheap they may be.

any way to fix it, root or custom tom

You'd have to search for that -- the forums at XDA-Developers.com are a good resource. The ability root depends on if there's a known root exploit for that device, and a custom ROM would have to be developed for that specific device by someone who's interested in it.