Well, thanks for all the help guys. I am soon going to put some values of FPS up here, if I have time. For the moment I can say, the new 304.48 drivers almost completely removed stuttering for me, even the black death track seems fluid now, still some FPS drops visible though. But I am happy with the performance on my rig (i5 3570K@4.0GHz, 8GB RAM, GTX670 OC) for now. Still looking forward to the next official (non beta...) Patch increasing the performance even further
EDIT: it was indeed the case that there was no key assignment to open the console. Now I managed to get the FPS shown on screen. Black Death track I got now MIN: 0 (don't ask me why, probably the first two seconds after loading), AVG: 55, MAX: 172. Looks like I can live with that.
EDIT2: I still get massive framedrops when something is exploding. Which setting has the biggest impact on this fact? I could easily live with less eye candy on this side, but the framedrop down to 15-20FPS in the black death track when the bombs on the runway explode is ridiculous...