In an interview with Video Gamer, senior producer Vincent Pontbriand tells more about the developement of Assassin's Creed: Unity and explains that it will be the same frame rate and resolution for both Playstation 4 and Xbox One to avoid debates about best version:
"We decided to lock them at the same specs to avoid all the debates and stuff."
Pontbriand also states that it is the CPU rather than GPU that prevents them from making an even more lifelike game:
"Technically we're CPU-bound. The GPUs are really powerful, obviously the graphics look pretty good, but it's the CPU [that] has to process the AI, the number of NPCs we have on screen, all these systems running in parallel."
Finally Pontbriand tells how this has affected the development at Ubisoft Montreal:
"We were quickly bottlenecked by that and it was a bit frustrating, because we thought that this was going to be a tenfold improvement over everything AI-wise, and we realised it was going to be pretty hard. It's not the number of polygons that affect the framerate. We could be running at 100fps if it was just graphics, but because of AI, we're still limited to 30 frames per second."