Finally getting close to finishing our iPhone game here, but am having a significant problem getting an acceptable frame rate on anything later than a 3G(S). Testing on the 3G gives us around 50 - 60 FPS, but we can only get about 9 - 20 on our iTouch (same specs as the iphone 4.)
Our initial impression is that it has to do with the shaders. Neither I nor the other guy making this game new about the alpha test-based shader performance issues and just slapped a Transparent / Cutout / Diffuse / Soft Egde Unlit on everything. (whoops.)
My question is why are we seeing such a big difference in performance between the two models? If anything, shouldn’t the Touch perform better with its higher specs? Also, do you have any suggestions on what alternative, mobile-friendly shaders that we can use that support alpha? (Current research seems to indicate Transparent / Vertex Color.)
Thanks! 
(Can provide more information if necessary.)