What does the Performance>Track Detail setting exactly do? Does it simplify the road mesh? Or it just hides some objects around the track while keeping the road mesh intact?
It reduces track side assets. At Long Beack for example you can see trees and spectators get removed when going from ultra to medium. They would be more but that is just something easy to notice.
So in theory you're good with high rather than ultra 02: OPTIONS AND SETTINGS - Project CARS 2 Scroll a bit down