Funny... LFS under Windows Vista for me ran perfectly fine. Normal FPS, same I get in XP. My FPS is always somewhere in between 35-60 or 70. Just depends on how many cars are around.
I eventually noticed performance got unplayable, then I realized the little csrss.exe trojan or whatever slipped past my antivirus. I decided that my friend was right, Vista has security issues, so now im back to XP.
Funny you had problems, this is my computer:
Athlon XP 2400+ 2.0GHZ, 1GB RAM, 80GB 7200RPM, GeForce 6600LE 256MB. The 80gig is what I have XP on, I was using Vista on a 40GB 5400RPM drive just for testing purposes.