If it only does this during games, or a specific game, it could be a few things, starting with the game itself. The app you installed could be using up to much of the resources on the tablet which would cause freezing. Also if you have other apps open (just changing screens doesn't close an app) then that would also cause you to be low on resources. It is best to actually close any apps that are open (even if not being used at that moment) before using anything that is a resource hog like games and videos.
You can add to that list of possible causes your connection. If you are on a Data connection, your carrier/service provider could be limiting the amount of data being used or its speed. And if you are in an area that doesn't get good strong service it would also cause this. If you are connecting via WiFi and haven't turned off data while doing so, that can make your tablet act up as well. Then there is also if the ISP is dropping the connection or the modem/router has any issues. These can cause this also.