I see you have Windows 10 installed. Have you installed the Anniversary patch?
Reason being is that the patch auto-enabled Microsoft's game recording software GameDVR (their version of Shadowplay).
It apparently has been reported to cause major stutter.
To turn it off, log into the Xbox App (just start typing Xbox on the start menu search)
Sign in (will be done automatically if you normally sign into windows)
Select the Cog icon (bottom left of window)
Go to GameDVR tab and turn it off
Reason being is that the patch auto-enabled Microsoft's game recording software GameDVR (their version of Shadowplay).
It apparently has been reported to cause major stutter.
To turn it off, log into the Xbox App (just start typing Xbox on the start menu search)
Sign in (will be done automatically if you normally sign into windows)
Select the Cog icon (bottom left of window)
Go to GameDVR tab and turn it off