ATM the track is unusable; performance used to be bad only on the main straight but now it's across the entire track. There was a fix for it by adding the ai after starting a session or something and lowering track detail also alleviated things, but there´s no legit reason to let an official track be 70 FPS SLOWER than other graphically demanding official tracks under the same graphical settings. I took these screenshots a while ago, didn´t change any settings between sessions. Nurburgring 24hr: Nurburgring GP: Sebring:
