It's not fair to blame C2 for these problems. Nobody ever claimed that a C2 program would perform perfectly on every platform. It's obvious (and stated) that mobiles run much, much slower than desktop PC's. But even with a desktop PC there are limits. You wouldn't put a million sprites on the screen, see the frame-rate drop to 1 fps and then blame C2. There are limits and you need to test for these limits from the beginning.
As an example, I recently decided to try my hand at developing a mobile game. Since I didn't even have a mobile with a touch-screen, I went out and bought the worse one I could, so that I could test on it. I was aware from the beginning that I'd have to be careful not to throw too many objects around and although I do most of my testing on the PC (I have a very powerful PC) I make sure to test on the phone at least once a day. It runs around 30fps, sometimes a bit lower. But if it starts to drop to 20fps, I know I need to make changes to my game. It's not because C2 is bad, it's because the phone is bad. If I developed the same game using a different program, I'd still have the same problems - the phone wouldn't suddenly become more powerful.