I am just really curious whyoverdraw / fill rate such an issue on Mobile Dev (eg. iOS/Android) ?? I am asking this because from hardware perspective, PowerVR MBX Lite is basically the Dreamcast GPU - in the same class as NVidia TNT 2; while the more capable PowerVR SGX is about the same class as GeForce 2 (? or is that GeForce 4?). On a historical perspective, overdraw / fill rate was never really an issue on desktop, but for some reason on smart phones like iPhone and Android, as powerful as they are at processing polygons, but if some 2D particles are covering the screen and your game grinds to a halt. I just don't get it. Why was this never an issue on the desktop GPU and why haven't they (GPU vendors) learn from the past?