I only have an ATI card, so I can't vouch for the Nvidia folks but this trick worked for me.

Since we are all running WOW in windowed mode, the 3d processor may not work at it's best unless the desktop refresh rates match the settings in the video card control panel.

0. Close any open WOW's
1. open up the CCC control panel by double clicking on the ATI logo next to the clock.
2. click "display options" on the left (assuming advanced mode)
3. select the "3D refresh rate overide" drop down and select "Desktop Rate"
4. Click OK
5. Start up your WOW's and enjoy

Don't forget that if your FPS is limited to 60, you can disable "Vertical Sync" in WOW - Options->Video->uncheck "Vertical Sync"