Going to need to quantify the stutter you people are experiencing with something like
CapFrameX. I recommend capturing a plot at your usual settings in the SRV training mission while you're inducing perceptible stutter.
This is about four minutes of me burning around on my main system (5800X3D, RTX 4090, 144Hz VRR display) at my usual settings (4k, 1.25x SS, custom ultra, 138 fps limit):
A few spikes, but nothing noticeable. If there were perceptible stutter, or even a loss of general smoothness, those frame time variances would be much worse.
It might be worthwhile to force a GPU or CPU limitation (by adjusting settings to create a bottleneck) to see if either seems smoother than the other.