Earlier this week Apple released Snow Leopard Graphics Update 1.0, a driver update for Mac OS X 10.6 that improved performance in some games. Game developer Valve – the company that makes Portal and Team Fortress 2, two games affected by the update – has posted a blog entry explaining how the update affects its games.

“We are seeing dramatic performance improvements on 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) and MacBook Pro (17-inch, Mid 2010) models,” wrote Valve. Those performance improvements can improve frame rates in games from 15 to 120 percent, depending on the game, hardware and video settings, Valve reports.

In releasing the update, Apple specifically indicated that Portal and Team Fortress 2 would see performance improvements on certain Mac configurations. Apple also indicated that Blizzard Entertainment’s StarCraft II and Apple’s own photo software Aperture would see stability improvements.

Valve Software indicates that Apple’s driver update made “low-level implementation changes” that improves performance across the board, and “removed some implementation inefficiencies” that improved the quality of graphics that use “occlusion queries,” a technology that Valve uses throughout its games, especially for realistic lighting effects. The blog entry features a short video that demonstrates the difference in image quality with these effects on and off.

Valve is hopeful that other improvements Apple could make to its OpenGL driver technology will further reduce bottlenecks, as well. The company specifically wants to see Apple to implement the uniform_buffer_object extension to OpenGL and GL Shader Language (GLSL) v1.3.

“We’re very excited about the performance improvements that Apple and the GPU vendors have been able to deliver this summer and we are working with them to further improve performance,” wrote Valve.