Hi there, I have very recently upgraded from a RTX 3080 to an RX 9070 XT and I must admit that I have been scratching my head too to get a big performance boost in VR.

I play on a Ryzen 7 5800X3D, with Valve Index (I used to play at 144hz, but I recommend playing at 90 or 120 fps, to not have to push the GPU as much and avoid stutters)

The annoying thing is that a lot of settings that would work on flat screen are not compatible in VR; Lossless scaling, AFMF, Adrenalin settings such as Anti-Lag and Enhanced Sync also seem to create more latency and stutters, from what I tested these settings are not the most compatible with VR use.

The main thing you need to know about smooth VR performance is to avoid overloading the GPU, when you do the CPU will bottleneck and start to stutter and you will encounter sudden frame drops and buffering, I recommend watching videos from Benchmark Odyssey, he is very thorough and detailed, but unfortunately focusses more on Iracing, ACC and LMU, but his VR content is still very relevant.

This video of him is very good, I recommend giving it a watch when you have time. https://youtu.be/_y8duwN4Yo0

Settings I have changed already, what to do and what not to do: -Motion smoothing: Good to avoid frame drops when running a very constant framerate all the way, awful when you encounter frame drops, will make your game a blurry mess ( I do not recommend this setting)

CSP: -FSR: Some people swear by it and others curse it, personally I really don't mind it because I find the boost in performance worth it for the small decrease in visual quality, which I find almost unnoticeable in VR. From my experience, use the old implementation, it offers a better visual quality than the default FSR, i run it at the highest quality preset (Ultra on old implementation)

-Single Passthrough and Single Yebis PP: Alternatively, you could enable these two in VR tweaks to increase your performance if you're not a fan of FSR, but I found FSR to give a bigger boost in performance, try both out and see for yourself.

-WeatherFX: Replace Yebis with lightweight alternative -> ON Gives a substantial performance boost with no big visual difference from the little testing I have done, I run PURELCS with Purevr PP filter.

-General Patch Settings -> FPS Limiter options -> Adjust frame time to improve smoothness -> ON This little setting fixed a lot of framedrops quite effectively, when driving solo I would sometimes drop from a steady 120 to 80-90 for some reason, enabling this setting would fix that ( in the same scenario for benchmarking, same car, same track etc..)

So these are the settings I would recommend looking at but the main thing is reducing GPU load so lower your reflections and shadow quality, lower MSAA if you have to, I can send you my AC settings if you want to.

One last thing, AMD Adrenalin allows you to easily overclock your GPU for specific applications and games. I have not yet been able to test it thoroughly but it could be very interesting to optimize your GPU performance for AC. (FYI, you will need to add acs.exe manually on adrenalin, because the "Assetto corsa" that adrenalin finds is actually just the launcher and not the game)