I play this game with probably lowest GPU around here. Actually... you can't really go lower cause it's in minimum system requirements. It's GeForce GTX 260. With 896 mb.
And... it's still playable. I can even have great races. Only if I survive those damn starts (and they're, ofc, most demanding part of the race for GPU) I'm fine. And if it's dry, if it's rainy... I have to "take a look back for NO REAL REASON whatsoever"
- just to get through that GPU demanding part of the game. Yeah, I know, it sounds funny but that's what I do.
Until I buy some better GPU and.... I'm in the process.
My processor is quite good actually it's quad i5. So it's not AMD as you can see.
That helps I guess. A lot.
So... as you can imagine... with this weak GPU on board, I must have done many graphic experiments and here's one fact that I haven't seen anyone else menitioned.
Tracks in PCars are so different in amount of stress they put on (my) GPU. And processor also I guess.
And... it's not that simple as you may think, I mean it's not like Nurnburgring is the toughest one and some small/short are best for my fps.
For instance - try Oschersleben track and Monza. If I get ~60 in Monza, I got ~30 at Oschersleben.
Why ? I'm puzzled but I think it could be... number of objects around the track itself and how far are they from camera/player. You can't even say it's because some look beter than other - Donnington look much better to me than Oschersleben but it's much less GPU demanding. Confusing, I know.
In any case.... you can get VERY different results on different track, that's I've been trying to warn you about, so make sure or that you test on the same track as someone who's graphic settings you use for testing.