I've seen a good 20-30% boost using the tweaks Stereo mentioned in another thread a while back about forcing Racer to use certain threads.
If you just watch CPU usage in Racer it hammers just one core usually and since that core is doing everything from GPU batch prep, Racer physics, audio, controllers via DirectPlay (I assume) and everything, then the slow FPS are the end result of a blocked up CPU.
Ideally the threads can be split and you can run like that but until Ruud makes it reliable to do so it's not really a workable solution if you want Newton or Onyx stuff to work nicely.
It certainly would be nice to have a way to manage your own thread profile, so you had a list of all the threads in racer.ini and could assign the core number you wanted it to run on... or just an automatic load balancer that would watch a Racer session and generate ideal thread splits for you!?
Not sure it's so trivial to actually make reliable multi-threaded code though, as I'm sure Ruud mentioned a few years back!
I guess if you could at the very least move graphics to it's own core you'd hopefully retain a solid Racer platform for scripts/physics/audio/controls, and then the graphics can be free to run as fast as they can on another core... hmmm...?!
Dave