Yes, the "mouse lag" is back with a vengeance in Snow Leopard. While not nearly as noticeable as it was in Leopard, it' s still there nonetheless.
Thanks to Kabyl for supplying the x64 Disabler and the edits to allow ONLY AppleUserUpstreamClient to be disabled. This problematic KEXT causes a slight system stutter on Nvidia 8*** series and above would notice when using iTunes or Quicktime.
NOTE: THIS ONLY DISABLES APPLEUSERUPSTREAM.KEXT NOT INTELCPUPM!! YOU' VE BEEN FOREWARNED!!
Enjoy :)