My game performs beautifully at 30 fps on both iPhone 4 and iPhone 3GS devices when compiled with Unity iPhone Advanced 1.7. However after upgrading to Unity 3.3 it runs at 9 fps on iPhone 4 (haven’t yet tested on iPhone 3GS).
Why is Unity 3 performing so poorly?
I’m building both with the the Fast but no Exceptions option. Literally nothing has changed between these projects!
iPhone Advanced 1.7 has no support for the iPhone 4’s native resolution. Unity 3.3 does, so you’re running at a resolution 4X that of the iPhone 3GS but with the same graphics capability. Either optimize the graphics (fillrate is killer, so try to reduce transparency etc.), or change it to use low resolution in the player settings; that way you’re using the same resolution on the 3GS as on the iPhone 4.