windowscentral[.]com/how-disable-and-remove-game-bar-windows-10-creators-update
Game DVR, part of the Xbox Game Bar, records video in the background while you game so that you can grab a clip of an epic moment that happened out of the blue. This recording also takes up system resources, so if your rig is already chugging along trying to run an intensive game, you can disable Game DVR without fully disabling the Game Bar.
If you have a Windows 10 PC and don't plan on doing any sort of gaming at all (or you just don't want to use Game Bar), you can disable the Game Bar completely. This means that nothing will happen when you hit the Windows key + G shortcut on your keyboard or hit the Xbox button on your gamepad.
My wife plays the typical GOTD weekend games, and while the game bar activates, it does nothing for her other than add a bit of confusion.