Running the Steam VR version here 3700x + 16GB RAM + 2070RTX
Currently playing with settings but found a big win I thought I'd share. The game seems to ignore running in windowed mode when you launch in VR and also runs at native res (again on the monitor) - despite telling it otherwise in the settings when launching the non-VR version.
Set set fullscreen="0" and the resolution on that line to 640x480 - I saw a big improvement in performance in doing this ~20%
Also a big annoyance is the pop in - you can fix this with <ground_cover clutter="true" enabled="true" lodScaling="0.