optimizing iPhone OpenGL ES fill rate

Question

I have an Open GL ES game on the iPhone. My framerate is pretty sucky, ~20fps. Using the Xcode OpenGL ES performance tool on an iPhone 3G, it shows:

Renderer Utilization

Answer 1

Look to Apple's "Best Practices for Working with Texture Data" and "Best Practices for Working with Vertex Data" sections of the OpenGL ES Programming Guide for iPhone OS. They highly recommend (as do others) that you use PVRTC for compressing your textures, because they can offer an 8:1 or 16:1 compression ratio over your standard uncompressed textures. Aside from mipmapping, you seem to be doing the other recommended optimization of using a texture atlas.

You do not appear to be geometry-limited, because (as I discovered in this question) the Tiler Utilization statistic seems to indicate how much of a bottleneck is being caused by geometry size. However, the iPhone 3G S (and third-generation iPod touch and iPad) support hardware-accelerated VBOs, so you might give those a shot and see how they affect performance. They might not have as much of an effect as compressing textures would, but they're not hard to implement.