Its fast. I don't have any games where I can make measurements, but there are some very clear speed ups, especially for Glidos games. Many games play movies by sending 565 texstures; this is obviously sped up. All the LFB writes in Glidos get turned into 565 textures too, and that is faster. Also the Glidos VESA support gets turned into 565. Specifically, Grand Theft Auto, Descent II and Redguard seem faster.
On the Windows side, can't see much difference in Red Baron, but Unreal seems very much smoother. Actually its rediculously smooth. Although I have a GF3, I don't find all D3D and OpenGL games runn smooth. One that did was Max Payne; it really stood out as smooth, and Unreal now seems every bit as smooth as that. No measurments, so perhaps I'm seeing things.
Only one problem, Redguard lost its nice yellow hazzy sun in favour of a big black sqaure, so I had to disable the new method for alpha tesxtures. Redguard is the only game I know that uses them, and it uses them only for the sun, so it doesn't really matter that we are not ussing the fastest method.
Anyway, very nice bit of work.