Since LFS engine runs at 100 Hz and if your screen is set to any other refresh rate than 50/100/150/200 Hz you will encounter some micro stuttering even with vsync on.

This will be fixed in the upcoming big LFS update, but by that time Lossless Scaling can help smoothing things out at the expense of some latency and some almost invisible artifacts.

Is short LS can fix the vsync by generating the proper frames to fill the gaps.

Lossless Scaling is a paid program available on Steam.

An example setup for 75 Hz and possibly 90 Hz:

LFS options:
1. Run LFS at borderless window mode (F11)
2. Set the vertical sync to [no]
3. Limit in-game frame rate to < 50 fps > (if you have 120+ Hz monitor, limit it to 100 fps)

Lossless Scaling options:
Frame Generation:
Type: LSFG 3.1
Mode: Adaptive
Target: 75 (75 = 75 Hz) set to your refresh rate - if it's above 100 Hz, limit the LFS fps to 100 fps and put in the target for example 120 (120 Hz), for 90 Hz - the target should be 90.

Capture API: DXGI
Queue target: 1

Scaling set to Off.

Rendering:
Sync mode: Default
Max frame latency: 1
Draw FPS: On

And then press the blue Scale button and switch to LFS or you can set a hotkey in the settings (I use F4).
If everything is set correctly, in-game you should see the "50 / 75" at the left top corner and the motion... should be smooth.

Tomorrow I can add some comparison videos / gifs.

Lossless scaling is nice. Worth noting this may be a driver-level feature for some radeon and RTX users. Nvidia smooth motion, AMD Fluid Motion Frames.

Also a fun trick in lossless scaling is offloading it to a 2nd GPU (or your iGPU if you have dGPU and iGPU)

I have RTX 4060 and the Smooth Motion doesn't work with LFS, it only works with DX11, DX12 and Vulkan APIs.

The other thing is Lossless Scaling also supports adaptive frame generation, which is the key feature for LFS and 60 Hz / 75 Hz, not only fixed multiplier 2X / 4X etc.

Nvidia Smooth Motion doesn't support adaptive framegen and there are many compatibility issues, I only managed to get it working with BeamNG.drive (37 fps -> 74 fps). On the plus side the latency is a bit lower than LS.

I don't know much about the AMD Fluid Motion though, but I'm guessing it has similar limitations.