Just recently we heard about an update to Microsoft's SDK for Xbox One that would enable better usage of the eSRAM module within the console. Now, the same group that leaked the updated SDK have also said that the Xbox One had received a bump in CPU performance in late 2014.
The hacker group known as "H4LT" claims that Microsoft had unlocked a seventh CPU core to be used for games back in October of 2014, leaving just one remaining core dedicated to process background information and power the Xbox OS.
The unlocking of a seventh core played a role in games that required additional hardware resources, such as Assassin's Creed Unity, to perform better, helping to minimize what little difference exists between Xbox One and Playstation 4 visually.
That being said, the unlocking of a seventh core shouldn't be seen as a performance boost to the Xbox One, but instead a choice of balance for developers that may want extra horsepower to drive resource-hungry titles. Should a game take more power from the seventh core, power to the Kinect will be limited, keeping voice commands relating to the system OS available, such as the "Xbox, go home" command, and limiting voice input/control to games themselves.
It's evident that Microsoft is leaving no stone unturned when figuring out how to squeeze every ounce of power from its flagship console to better support game performance. This doesn't play against Microsoft's media ambitions for the Xbox One console, it just shows that there's greater emphasis on delivering on a better game experience. As of this time, Sony's Playstation 4 console is still locked to six CPU cores when powering games.