hello, thanks of you for your reply! :)
I optimised my backgroud, reduicing my memory use to 12 mb, wich is good, but changed nothing to my heratic fps.
I have 161 objects, wich is too much so, and if i go down under 100, the "pb" is really less present, but still there. I will work on that now.
2 things :
I think that I realised that the Ipod4 seems to not like not straight solids : if all my solid are straight like in Super Mario for example, with angle at 0, the fps tends to not move so much, but if i do solids (like a descent of 45 degrees for example), the fps tends to fall.
Not sure of that, but that's my impression compare to the tests i've done.
Excuse me, I forgot to specify it : my test were on CocoonJS.
By the way, my fps were always moving between 42 and 62, never under 30, but never stable, wich makes the games creating some kind of "pause" when the fps falls under 50 during an half second, when i try it on CocoonJS, and what is not nice when you play.
So my questions are :
Is it something i will have only on the test, or what i see in it is exactly what i get ?
Last question : is it possible to force the game to play at 30 fps for example, to avoid this fps fall ?
Thanks again for your help and excuse me for my broken english :)