Alt + Enter

Since I pressed Alt + Enter, game is kinda working bad now. When i alt tab, it much slower in react then before; sometimes when i start game it start in window mode. Tryed reinstal, didnt worked...Overall, i know it sound funny, but game worked fine until i pressed ALt + enter....

https://support.microsoft.com/en-us/help/81823/alt-enter-switches-between-window-and-full-screen

It makes the game go into windowed full screen i believe.

If you go into graphics options you can toggle it there. Alt-tab is much slower in true fullscreen and super fast in windowed borderless.

Sometimes you get a better framerate in one of the modes. You'll have to check what works best for you.

I think it even says most of this in the game if you mouse over the setting.

Worth noting is that amd freesync works in windowed mode and fullscreen while nvidia enhanced sync only works in fullscreen.