You should get a performance gain when they implement the HSR driver mode. Currently it appears to corrupt the graphics in Quake 3, and FAKK2, but works great on Soldier of Fortune. (At least in my system)
If you have SoF and any Voodoo above V3/ DX8, and the latest WHQL drivers with the HSR in them, try this;
Make a text file
cut and paste this into it;
@ECHO OFF
SET FX_GL_HSR=1
SET FX_GL_ZCULL_ENABLE=1
SET FX_GL_ZCULL_FAR=32767
SET FX_GL_ZCULL_NEAR=4
sof.exe
Put this in your sof file wherer your sof.exe is. Change it's name to beta.bat.
Run beta.bat by clicking twice on it. set your visuals up a notch or two(It won't accelerate if your cpu is the bottleneck) I suggest 1024x768 with high details and 2xfsaa if you're on a Voodoo 5 5500.
This technology may wind up only being implemented in OGL, and may never be properly implemented. But there is hope shown in this example. In Quake 3a on certain settings I would guess that I gained around 30fps with this.