I Matrixreal your game is really smooth and playable...
but I want to know more about
" everytick -5*60*dt"
you sure that my game is playable on iphone 4 ?
i will release new version will more and best performance ...
about every tick
if you want like my game , the pipie moving on every tick (set pipe.X-5) you replace it by (set pipe.X-5*60*dt)
other trick to get maximum performance is to destroy object outside layout (that preserve some memory) and to check collisions enable only if is near player for example (if x of pipe equal or less than player.X+2)
dont forget to animation ... set animation to play from begining only if its on screen (that optimise much of performance in my case)
and the final trick is to do what ashley and aphrodite say ... memory magement of ejecta and (set to transparent of layer, sampling to point, clear background to no and PIXEL ROUNDING TO ON)
all that testing performance take me time of 5 days and here is final what i can do