Gamespot: That's according to a file discovered in a leaked version of a forthcoming preview update. by Chris Pereira
'Twitter user WalkingCat reports the addition of a dll called "gamemode" in the latest build of Windows 10 (version 14997). A subsequent tweet notes it "looks like Windows will adjust its resource allocation logic (for CPU/[graphics] etc.)" for the purpose of prioritizing game performance.
'WindowsCentral lends further credence to this, indicating that its sources say it works similarly to how Xbox One runs a game. The feature will reportedly launch as part of the Creators update and will be enabled for Windows Insider users soon.'