In a presentation yesterday at the Game Developers Conference by Microsoft, DirectX 12 was announced across the Windows 8 range (Xbox, Windows 8 phones, and Workstation) to reduce CPU usage by 50% while giving better controls of the video memory and GPU by a means of a thinner API and newer rendering features.
In the past DirectX acted as a go between for game developers to allow for smoother cross hardware development, meaning most of the hardware features could not be accessed and although the DirectX 11 API has seen some great boost in performance its still not as good as it could be.
Working with hardware vendors and game developers; the Microsoft team has spent the last 4 years working on getting the best from the new interface which from reading means cutting down the api and allow the developers to access the hardware direct.
What this should mean for games supporting DirectX 12 is that they should be less fluff getting in the way and games can be designed to fully exploit all the hardware features currently underutilised.
Even non DirectX 12 games / hardware should still receive benefits too with this leaner API but at the moment Microsoft have not confirmed if it will be available for Windows 7, but should be released in 2015 which means it may be time to upgrade once the games start running on this DirectX version next year if Windows 7 is not going to be supported.