if I enable my 8500gt 512mb I get system + mouse lag

I've tried:
efi with efistudio from leopard
graphicsenabler=yes
nvenabler from osx86project
natit
removing appleupstreamuser and rebuilding extensions.mkext
disabling appleupstreamuser
booting with cpus=1
disable cool and quiet
tried voodootscsync though it is build only for core2duo

none of them fix the issue. the bug happens with a logitech mouse, bluetooth mouse, and apple mighty mouse

no matter what I try, the bug is there.

this issue happens in leopard as well, with the only fix of removing Geforce* and NVDA* kexts from /S/L/E and installing nvidia kexts with 9f9installer.pkg. This dosn't work with Snow Leopard as these kexts cause it not to boot. that leopard fix can be read about here.

what should I try?

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10.6.4 & Win 7
GA-P55M-UD4 f10 Graphics via DSDT ~ i7 860 ~ GTS 250