I am playing through an animation of about 90 images @ 480x320 each, and I am wondering with the images not being power of 2, will this be a big performance hit? I am programing for as far back as the iphone 3Gs. Also I am using cocs2d.
Let's see...
480x320 image will create a texture of 512x512 (next nearest power of two). 512x512 times 32bit color depth (4 bytes) equals 1 Megabyte. 90 times 1 Megabyte equals 90 Megabytes.
Your biggest problem will be allocating this much memory and caching it. Without caching the animation images, you'll have to load each image every time the animation frame changes. Loading 1 Megabyte from flash memory is pretty darn slow, I'm guessing > 100 milliseconds. So every time a frame changes, your app will stop for a fraction of a second. This will be a problem on the 3GS, and possibly the Retina devices as well if you use Retina images (each 960x640 image then requires 4 Megabytes texture memory).
You can only improve this by using PVR compressed images (use TexturePacker). Even halving texture size to 16 bit will probably not be enough for a smooth animation.