This has intrigued me. I'm going to be trying this out when I get home.
All I REALLY see are darker shadows and if that's all it takes to get 7 extra FPS, sign me up.
Edit: He also said to add/change this in the config
change two commands:
Explanation of his tweaks
in case you wonder what every command do, here is the explanation
improve the lighting by darkening the shahow and boost the hdr lighting a bit, no performance change for this part
boost extra fps for little/no image quality loss
turned down shadow setting from very high and gain extra fps
improved distant mountain texture, but would use extra system memory, no performance hit if you have enough memory (min 2GB)
improve quality of distant trees with little/no performance hit
adjust the vegetation and particles setting to boost performance
enable vsync to reduce tearing for no performance hit