One of the big problems with Nvidia's proprietary drivers right now is that they give you no control over the power settings. As a result, the card is often at it's lowest power setting, which makes Compiz and other composited apps look terrible. One way to solve this (aside from bludgeoning the Linux driver folks at Nvidia) is to trick the card into waking up when an action requiring compositing is anticipated.
For example, to switch virtual desktops I use Ctrl + Alt + Arrow (up, down, left, right). In this case, the graphics card could be told to ramp up on detecting Ctrl + Alt. The principle can be applied to any key combination longer than one, though I can't honestly say what gains in visual performance there would be.
This would ideally be a user controllable setting, with the option to let it be controlled by current power state (battery or AC).