Underrail heavy problems since Windows update version 1803

[ATOM]

Since the windows update Underrail got some serious issues for me. First on startup or switching to desktop the game often crashes or at least it takes a very long time. Second the mouse while ingame became extremely sluggish and slow, which makes it unplayable for me.
I already tried some stuff, but nothing worked so far:
-reinstalled the game
-disabled anti virus
-disabled fullscreen optimation and enabled run as admin on the .exe
-reinstalled the Microsoft XNA Framework Redistributable 4.0
-checked drivers and graphiccard settings

The game had a wired startup before, but at least it worked fine after that. Let me know if you might have a solution or if you have the same problems.

[Qiox]

The only weirdness I ever had was on startup where only the top left quadrant of the title screen would show up and the other 3/4 of my screen would be my desktop. Had to alt-tab 4 times in a row to get the screen to show properly.

Disabling full screen optimization fixed that issue for me.