I have downloaded the Xbox One X enhanced patch for the game (great job btw!) however I am unable to get the game to stay in performance mode.
I am running v1.60 of Witcher 3 and the option is available in the menu to swap from 4k into Performance mode. When I attempt this, the slider moves over as expected but doesn't seem to stick. If I back out of the menu and reopen the menu in the game, then the slider has moved back over to 4k.
I have yet to determine if this is just a visual bug (ie the slider always resetting), but figured I'd get it onto your radars.
I didn't find the right solution from the internet.