I must do some more testing.
But since doing this test I have been running my screen on 144Hz (again) and there is a big difference.
FS wont be running with screen set to 144Hz though, there is to much "going on".
I can not really define what the issue is, but it is not "smooth".
I am not sure what is worse, the big chunks of frame drops at 60Hz or the micro stutter at 144Hz.
But as vehicles also has issues when running on 144Hz I wont use that setting anyways.
I will set my screen to 59Hz again and do some more testing.
Edit:
So I kept walking down this road...
I can also set my screen to 120Hz (60x2=120) ...
Guess what ... mayor difference when setting the FPS to "free", I get a rock solid 120Hz and my game is smoother than ever (except for animals animation).
Also vehicle speed does not seem to be any issue as it is with 144Hz setting.
Screen set to 120Hz and game locked to 60FPS ... stutter!
This has only been short test sessions.
I will need to try this more to be sure about these result!