VR games struggling to run well even though GPU and CPU usage are pretty low

i have a quest 2 running through a decent link cable on my pc (14600kf, 4070 super, 16gb ddr4). Problem is, no matter what refresh rate i set for my headset, perfomance is still poor. at around 3600x1800 resolution, my gpu is only at around 50% usage, and most of my CPU cores are between 20 and 50%. none of them seem to be that high. but framerates are usually constantly changing from the refresh rate to half the refresh rate(which i know is intended behavior). the steamvr performance graph shows my frametime jumping above budget often. the only solution for no man's sky i found was using 120hz and locking my framerate to 60fps to get a smooth experience.

is this a viable way to play? am i just CPU bottlenecked? i just cant play any games where the fps matches the refresh rate at all or most times, even vr chat has problems at 80hz with avatars disabled and low general settings. it can run at 80fps for half the time, but the other half at 40 fps basically.

any advice?