@Severne I have just bought 4070 gpu and I faced this problem. Vsync on and frame capped 60 in NCP with FG. My monitor doesn't have GSYNC.
When I load the sim everything is smooth but after some time start stutters. When I press esc and switch to menu then wait 1 seconds and turn back to sim no stutter but after some time it starts again.
Did you find any solution?