Comment by marzullo

I think it's only been with new DX12 presentation modes [1] that games can use "Borderless windowed" without input lag. Before that or without updated support, you would always get a noticeable amount of input lag when not using exclusive fullscreen. I played CSGO competitively for a while, and it was definitely enough to be annoying.

[1] https://learn.microsoft.com/en-us/windows/win32/direct3ddxgi...