“It was clearly a bit more complicated to extract the maximum power from the Xbox One when you’re trying to do that. I think eSRAM is easy to use. The only problem is…Part of the problem is that it’s just a little bit too small to output 1080p within that size. It’s such a small size within there that we can’t do everything in 1080p with that little buffer of super-fast RAM."
http://www.ign.com/articles/2014/02/10/sniper-elite-dev-explains-xbox-one-1080p-difficulties