I did a quick thread search and no results came back, so maybe this will be helpful to someone else too.
I'm running rFactor on a stock E5200 @ 2.5 ghz with 4GB of DDR2 RAM + a XFX 4870 1GB and I can run most tracks/mods at very high or max settings with up to 30-40 car grids. But, there are a few tracks that give me framerate slowdown--such as the Nordschleife and the new Yas Marina circuit.
Well, almost by accident, I stumbled across a little processor tweak that may help some of you out if you have a dual-core (or even a quad core maybe? I'm not sure) processor that isn't overclocked like me. What you do is go to the start menu rFactor icon, right-click on it and select properties. Go to the shortcuts tab (that should be the default tab in properties I think) and in the "Target" window, you should see this line:
"C:\Program Files\rFactor\rFactor.exe" Just add +fullproc (with a space in front of "+fullproc") to the end of this line, so it looks like this
"C:\Program Files\rFactor\rFactor.exe" +fullproc
Click okay, and the properties menu should close.
Basically, what this command does is allow you to take advantage of both processors while playing rFactor. Apparently, by default, rFactor only takes advantage of a single processor. I have just briefly tested the +fullproc tweak at the Nordschleife, and I am seeing a 10% framerate increase, and no longer dealing with any framerate stutters at that track. I have been running at 1920 x 1080 resolutions, and I may drop those down to 1680 x 1050 and see if I find further improvements. I haven't tested this on a race grid full of cars in front of me, but I'm hopeful I will see +/- a 10% framerate increase there as well. Also, I have noticed that load times have improved slightly with this tweak as well.
As I said, my processor is stock, and I can't OC because my HP motherboard won't allow it. In order to OC it, I would need to get a new mobo, or just upgrade to a G33 chipset-compatible E8xxx dual core, or a quad-core like a Q9xxx or Q6xxx. I'm not ready to spend that kind of money right now, so this tweak will hopefully come in pretty handy for now, at least in rFactor.
Here is a link to one of the threads where I found information about this tweak:
http://forum.rscnet.org/showthread.php?p=3204295 Apparently, this is pretty old news, as this thread dates back to 2006
But hey, it's news to me and maybe some of you can make use of it.
Word of warning:
if you decide to use this tweak, you do so at your own risk.
It hasn't happened to me, but some people have reported that this tweak gave them no performance improvements and/or caused rFactor to start acting "glitchy" or just generally not perform well.
But, if you have a stock dual-core, or even one that is overclocked, you may be interested in trying this out. It's working well for me so far.