Actually, many users are going through this problem. I heard that there're problem in loading time, physics, distorted sprites, crashes and so on.
In my experience, I had some plugin issues in my game but the game worked in stable version of C2. After upgrading to beta, now physics are crush so it doesn't work now.
But if u wait patiently, with all bug fixed, you will find awesomely improved fps in your game.