@Zhenmuron:
First of all I suggest to maintain FPS for your game...
Do one test, Use debug draw and set the opacity of every sprite to 0 value..
This will give you maximum FPS possible in your game..
You will get the idea how can you increase the FPS.
http://allseeing-i.com/Performance-tips-for-Cocos2d-for-iPhone
There are several steps to reduce it...
1 -> As boundary of your platform do not use cpSegmentshape..
Use polygon shape for your boundary.
2 -> Decrease the mass of the your dynamic bodies as compared to static shapes...
3-> Adjust damping ratio for your game.
4 -> Adjust Gravity for your game
5 -> Maintain your FPS..using setAnimationInterval
6 -> Set perfect Hash(static and dynamic) value for your space
1=> At very slow FPS sometimes, poly shape even not detects, This is limitation of physics engine, due to design flow...
If this happens in my game, i hack the chipmunk function locally to maintain such thing.(not much idea but one tricky shot helps me in this). I know this is not good thing, so i generally avoid these kind of "games" even..
2,3,4 => bad steps generally ever,---- But we are the God in our physics system we have power to do..! Use power !
5,6 => These is general ways to improve the FPS, you can easily find on cocos2d forum..
I am getting 60 FPS in my iPod Touch 2G( slowwest iphone version ) with debug draw ..
which contains 250 circle balls and four sided boundaries..
Cheers..
Max