Re: 8600M GT+Compiz=Slow Animations and Black Window Bug
The PerfLevelSrc hack is only a semi-magic incantation. It's actually stolen from the vendor supplied Windows drivers for many laptop cards. I think the author of nvclock speculated on the meaning of the "0x2222" but, no one from nvidia has officially said what it means. On 7xxx mobile cards (using < 169.* drivers) it effectively disables gpu frequency scaling but, it's not clear what else it might do.
On mobile 7xxx cards, without the PerfLevelSrc hack, a composited desktop is painful on the eyes (though, newer drivers are MUCH better than they used to be when getting the card to scale to full gpu speed nearly took an act of god).
I don't know enough about this stuff to claim to be an authority but, basically, the nvidia driver can't (at the time of this writing (I see it coming in +169.*)) give sane default clock speeds for AC/battery power so, if the PerfLevelSrc hack won't work on 8xxx series cards, illogically, your best bet for a smooth composited desktop is probably to generate enough activity on the video card to force it to constantly be at the highest possible frequency. Oddly enough, you can probably do this by playing around with the compiz benchmark plugin, forcing it to sync to vblank and putting it completely offscreen.
A few other things to try would be to reset all the nvidia-settings stuff to default (few of the settings jive well with the 7xxx series of cards), go into the compiz settings manager, check General Options->Display Settings and deselect "Detect Refresh Rate" and then manually move the slider to your laptops refresh rate. It used to the be the case that some laptops would be detected as having a refresh rate of 59.9Hz and it would get rounded down to 50Hz. Needless to say, the desktop was not pleasant at that refresh rate.