After moving from 4.2 to 4.3, windowed fullscreen on a 4K setup no longer performs better than fullscreen, although it did in 4.2. Did anything change that would cause this, or is there a setting the player might have missed?asked by seikenn

Yes that is very odd because nothing has changed on our end between these two patches on the renderer side.
Also fullscreen mode is literally the same as borderless mode from the OS perspective for a while now so they shouldn't be any difference to begin with.
Once windows recognizes a game in borderless using the entire display screen it can put it into an optimized state.
Our fullscreen mode simply forces a borderless window maximized to the screen. On top of you can change the rendering resolutions in this mode.
it does sound like something else has changed in your environment. Are there any other people who can confirm this behavior?

Cheers
Silvan-CIG