I've played a little on my TV with the CCU over Wifi but not enough to determine lag, my Mac is hooked to gigabit straight to my router. They do recommend 5Ghz

I've played a little on my TV with the CCU over Wifi but not enough to determine lag, my Mac is hooked to gigabit straight to my router. They do recommend 5Ghz for Wifi and being as close to the AP as possible. I can image if your AP is behind a wall or in a closet or different floor you get noticable delays as signals come in via reflections rather than directly.