Yes, I'd like to have subpixel aa, as well, but it is just unbearable slow for me. But NVidia knows about it and hopefully one of the next drivers accelerates it properly.
BTW, as I thought your mtrr is missing an entry, try this: (in your case):
echo "base=0xc0000000 size=0x10000000 type=write-combining" >| /proc/mtrr
I hope I have calced the size correctly.
Restart X and see whether it helps a bit. I also wonder why latency for your card is set to 0. This should slow down busmaster, afaik. (see http://www-128.ibm.com/developerwork...ary/l-hw2.html
) Or is this a PCIe card?