Stuttering when moving the Mouse in Fullscreen

I have the Problem with stutterings up to stop when moving the Mouse in Fullscreen. In Windowed Mode its okay, but less Perfornance then in Fullscreen.

Latest NVidia Drivers or one Version before, doesnt matter.

Edit: Config: i9 9900KS, 32GB 3200 DDR4, 3080.
GPU Load is like 5% while these stutters. Guess a D3D Problem or somewhat. Was Fine before SU5.