Let's be clear. We're posting this as "rumour" because we have to. The chances of it being real are about as likely as Microsoft announcing that all games will be free from now on and that they'll be launching a new console at Christmas.
In short, this is 99.9% fake.
A Spanish Xbox site has uncovered - by unspecified means - a "leaked" document regarding the apparent performance boosts that Microsoft's upcoming DirectX 12 will provide for the Xbox One system. In particular, a hearty 50% boost to the console's CPU and a 20% increase in GPU performance.
Rather bizarrely, nobody more reputable has seen this document. Just the guys from a small Spanish-language Xbox One site. For some reason, some sources are actually now considering that this is stone cold fact, complete with all the spelling errors. Of course, the hardcore Xbox fanboys are having a field day, going about their business of attacking PlayStation 4 gamers and - as they do so - making any regular well-balanced person with an Xbox One look bad. Heaven forbid we play a few video games and enjoy them without making everyone else who likes something different feel bad for doing so, eh?
So, why are we posting this? Well, it's Saturday night and we like a laugh. Not only that, but someone has to - as the kids would say - keep it real all up in here.
DirectX 12 WILL improve performance in certain areas and yes, it will be noticeable in some games going forward. However, if you think that your Xbox One is suddenly going to have the power to output everything at 4k and 120fps, then you really should just hold fire on trying to do anything more testing than making a grilled cheese sandwich.
Actually, don't take that as an official suggestion. We don't want to be blamed for any house fires.