theres a bug where the vr profile is missing for amd gpus and it ends up running lower power, I'm sure you can find the thread where they have proper instructions to fix it or just use corectrl to set the performance limit to high or something when the vrcompositor program is running, that fixes the frame times.

you can use the steamvr in built frame time graph, it can be displayed in the headset so that is that

there is really no need to be using windows just for vr anymore