I have ATI 6850 cards in crossfire mode. In GSC 2013, I can run the Mini Cars and the V8 Stock Cars with no problem. However. I get long stutters when driving the Formula R cars. The game will freeze and then pick back up 2 or 3 seconds later.
Exact same problem here with 6850 crossfire...even if the affinity adjustments work, there should be a better solution from the devs.
May not be their fault really - it's an older game engine and you need to be careful of what is running in the background. I was getting random sections of choppy gameplay in amongst fluid play on my machine - really bizarre and disappointing. I looked to what was running in the background, and I tried raising priority and processor affinity (my command line on the shortcut looks like this Z:\GSC2013\GSC.exe +fullproc +highprio). I removed windows update (that stole focus couple of times and was p*ing me off on a regular basis anyway). I notice that windows wlan agent service was running - even though I've no wireless card - I killed that too. Also was Windows Media player network agent - killed that (all with msconfig). Turned out that the REAL problem though - was having STEAM running in the background (doink). If you've got anything like STEAM or DESURA or even a bloaty virus checker that constantly phones home - kill them. Kill them all. Runs fine for me now. My machine is an i7 2600K GTX670 and Win7 x64 - I'm running all visual settings on max and have a G27 and TrackIR also going at the same time.
