I’ve had the same problem too. If I turn the settings as low as they will go, it smooths out and stutters once or twice every 30 seconds or so. I’ve dialed the options.lua file down to 30,000m, with marginal improvement if I don’t downgrade the graphics as well.
I don’t really know how I can help, but I’m happy to do what I can. It’s probably worth noting that I have the stuttering in VR, but if I play in 2D, it’s as smooth as one would hope.