I don't know if you're interested in this sort of performance increase but have you tried notaz RAM timings tweak?
http://dl.openhandhelds.org/cgi-bin/wiz.cgi?0,0,0,0,8,154
I noticed up to 5 fps more (25 to 30) using this tweak with GL Quake. I'm curios if it would help your engine too and how...