Games Stuttering while focusing game window? | Shadow (ENG) | Page 1

I'm experiencing lots of dropped frames while playing basically any game, even though the game's performance is quite good.
I have an example clip attached here using Forza Horizon 5, yet other games are the same.

The weird thing i noticed is, that it seems like issues only arise while the game window is focused.
I tried demonstrating this at the end of the clip by using a controller to exit the pause menu while the mouse is focused on the desktop (cursor is still locked inside the shadow client).
It's a little bit hard to see as forza instantly goes back to the pause menu if its not focused, but there is a small time frame where its apparent that the game runs really smooth.
You can see how bad the frame drops are after clicking back in, alone from the mouse movements though.

The clip: https://drive.google.com/uc?id=1elcVV65n-nBLsXEcffsc0eE8oukfNoH5

#Games Stuttering while focusing game window?