I'm not sure what my settings are but the performance isn't that bad, it actually runs better than Dirt Rally for me - that is when I'm in a forest in the rain in the latter. Then again I remember the performance not being so great last time I tried the pre-release build and I overclocked my CPU by over 30% (an i5 2500K from the stock 3.3 to 4.5GHz) so maybe it's quite CPU-intensive?
Nvidia won't release a driver specifically for Project CARS as they did with GTA V simply because GTA V was a huge release, they may wait for another big game like The Witcher 3 before they push a driver update which will contain optimisations for other stuff that came out between GTA V and that. Basically, yes, there will be a driver update with Project CARS fixes, but I can't imagine it's very urgent.