So i've tried the real vr mod and it's actually pretty straightforward to get running without killing your performance. First thing you'll want to do is make sure you've got a clean game install, then grab the mod and run that realconfig file to pick your performance settings, i usually go with medium as a starting point.

For the best experience, you'll probably want to tweak a few things. Dropping the shadows and reflections down helps a ton with performance, and honestly you won't notice much difference in vr anyway. Something i found really helpful was turning off those fancy rt effects if you've got them on, they look nice but they're not worth the performance hit.

The vr side of things is pretty simple, just make sure you're running at 90hz in your headset software, and maybe turn off that motion smoothing stuff since it can actually make things feel worse. Oh and definitely crank up the first person fov in the camera settings, makes a huge difference with motion sickness.

Good to know: one last thing that's made a big difference for me is closing everything running in the background before starting up, and making sure your gpu drivers are up to date. The whole setup might take a bit of tweaking to get just right for your system, but once you've got it dialed in it's actually pretty smooth sailing. Just remember to save your settings once you've found that sweet spot!