Back in April, Microsoft rolled out the Windows 10 Creators Update that brought with it many new changes, including to gaming. One was the Game Mode, a mode you could put your computer in to, in theory, allow a game to use more resources and therefore run better; however, the opposite appeared true. Since April, some users have also reported performance issues, including stuttering problems in games. Finally, Microsoft has acknowledged the problem is associated with the Creators Update and are working on a solution.
Right now the only way to test out the fix is to enroll in the Windows 10 Insider Program, which allows you to install in-the-works builds of Windows 10. That, of course, could bring issues with it as the builds are not finalized and may be prone to many problems. So, the fix to the problems is still in the works and not yet finalized.
The Fall Creators Update is looming as well, which is a likely candidate for Windows to target to release an eventual fix, if they get it in place by that time. You can see an updated list of changes coming in the Fall Creators Update, which mostly include various fixes and tweaks to design, UI, etc.
However, in the meantime you can send feeback to Microsoft if you are experience performance or stuttering issues through the Feedback app on Windows 10. Microsoft says the information users provide there will help them find a fix. If you do find yourself getting in on the Windows 10 Insider Program, or already are, Microsoft is asking to test out an app/game you had a problem in and let them know what happens. You can do that in the originally linked thread here.
Have you been having performance issues since the Windows 10 Creators Update? Let us know in the comments below!