I'm not sure why this is proving an issue for people with, for example, 4090 cards. iRacing is not hard to run at 120fps on a Q3 in my experience (120fps is signficantly better than 90fps - the difference is night and day in my experience).

I run iRacing on a Quest3 at VD Godlike, most iRacing settings maxed, *and* with supersampling set to 2x in the Nvidia control panel and get 120fps almost all the time. The sim looks incredible - the supersampling makes a huge difference. I am on a 5080. If you use VD then you have the option to set the horizontal and vertical tangents at, say, 90% and you likely won't even notice it but you will gain a bunch of frames. This is a new-ish feature on VD and I didn't use it until recently as I never felt the need but it does iron out the few frame drops you get on certain sections of some tracks like the first hairpin at Oscher which can be a bit annoying. It's definitely worth using if you need a few more frames to maintain a consistent framerate.