I'll have a look at the mipmap thing next week.
In regards to the slowdown, i would guess
- your AGP bus is misconfigured
- 512x512(pixels)*4(bytes per pixel)*2(read and write)*100(hz) is still a big number (200Meg per second)
- there is a 24 to 32 bit pixel conversion being done due to texture and backbuffer mismatch
- missing out the vram flag is not an option with ATI drivers
In regards to the slowdown, i would guess
- your AGP bus is misconfigured
- 512x512(pixels)*4(bytes per pixel)*2(read and write)*100(hz) is still a big number (200Meg per second)
- there is a 24 to 32 bit pixel conversion being done due to texture and backbuffer mismatch
- missing out the vram flag is not an option with ATI drivers