@cybereality said:
I do believe there used to be performance benefits from exclusive fullscreen but, AFAIK, this is far in the past. There is little, if any, difference now. And exclusive just makes it more difficult, black screens, slow alt + tab, worse support for odd resolutions, etc. It's just not worth it, even if there was some small 5 fps gain.
Exclusive fullscreen performs a bit better, but most importantly, it has much lower input lag since it can bypass compositing. Unlike some Linux window managers, Windows no longer allows disabling compositing, so exclusive fullscreen is now the only way to attain this.
Note that on Windows 11, you can enable windowed gaming optimizations which do the same thing. However, this is disabled by default and only works on DirectX 10, 11 and 12 games, not OpenGL, Vulkan or DirectX <= 9 games.