67% GPU sounds good. Don't think it's a resource issue then.
V2 models give much better fps than V1 models. So u should see significant improvements from using them.
Yes, vsync is always on.
Try to set rife_sc to 100 in SVP so it will not cause microstuttering from repeating frames when a scene change is detected.
Xenocyde, could vsync syncing cause microstuttering then? Cause every time i try to test with video-sync=display-resample it breaks the soap opera effect on panning scenes.
Try to test with it temporarily disabled by adding these in mpv config too:
# D3D11 renderer (default) is required for the HDR playback
gpu-api=d3d11
# disable VSync
video-sync=audio
d3d11-sync-interval=0
Removing vsync wait times from the equation should allow the RIFE generated frames to be displayed realtime. Even if u set it to 120 fps on a 60 fps capped monitor. xD