Performance mode will most likely suck on consoles lets be honest. Game looks amazing and made with 30 fps in mind. I dont mind 30 in a game like this tho so all good. Man i cant fucking wait for this one
There are several games with 60fps or RT modes that don't include those modes on XSS, though several games do support those modes as well. That definitely seems to be a developers choice thing and not a requirement on the Xbox side.
The only requirement seems to be that the core gameplay (the levels of the game) remains the same between the two, though they made an exception on the splitscreen.