Well, after a long and arduous process, I figured out what was causing this. In my Nvidia control panel I limited my frame rate to 60fps and set Vsync to half refresh rate (120Hz). For some reason this was causing my main thread to tank every so often, causing the stuttering I had.
I turned off the frame rate limiter and set Vsync to adaptive, and voila, main thread indicator is constantly steady, no tanking or stuttering and frame generation doing what it’s meant to do (70-120fps depending on where I am).
Cause wise, not sure. Maybe it’s because I was telling my graphics card that I want one thing (60fps limit) and I’m telling the sim I want another (frame gen, as much FPS as possible) and the two were fighting with eachother.
Ideally instead of fluctuations between 70 to 120fps I’d prefer a constant 60, so I left the FPS limiter in the Nvidia settings to off and just changed the Vsync to half refresh rate - that limited the frames to 60 but same stuttering issue. I’ll need to see if the in-sim settings have an effect.
Overall, positive result. Eventually.