Apple has released Snow Leopard Graphics Update 1.0 (http://support.apple.com/kb/HT4286). It contains stability and performance fixes for graphics applications and games in Mac OS X 10.6.4.
Snow Leopard Graphics Update 1.0 Addresses frame rate issues occurring in Portal and Team Fortress 2 by Valve, on the iMac (Late 2009 and Mid 2010), Mac mini (Early 2009 and Mid 2010), Mac Pro (Early 2009), MacBook (Early 2009 and Mid 2010) and MacBook Pro (15-inch, Mid 2010) or MacBook Pro (17-inch, Mid 2010) models.
It also resolves an issue that could cause Aperture 3, or StarCraft II by Blizzard, to unexpectedly quit or become unresponsive. Finally, it resolves an image corruption issue that may occur when disconnecting and reconnecting external displays while the system is running.
Snow Leopard Graphics 1.0 can be downloaded via the Software Updates component of Mac OS X’s Systems Preferences app.