I didn't realize my old post on this was in the MC25 forum, so I'm posting it again here.
When Media Center is playing music, it can cause stuttering in other programs/games.
It seems to be a fairly consistent stutter that occurs every second or so.
It does not matter which playback device is being used, or the output method (WASAPI or DirectSound). Even MC's Null Output device causes this.
My suspicion is that it's something to do with the way that MC updates its UI, as it happens roughly every second, and there have been weird bugs with that in the past where MC could cause windows of other applications to flicker.
Here is a video example showing these stutters on a frame-time graph while a game is running at 90 FPS in the background:
https://www.youtube.com/watch?v=BNkkrerKfi8Note that it only happens with MC, and not any other media player - and also occurs while resizing MC's window.
A consistent and easily-reproducible test I have found recently is to load up a fresh profile in Firefox 76 (current version) and visit this web page:
https://www.testufo.com/framerates-text#pps=240&count=1As soon as playback starts in Media Center it is no longer able to sync, and the page stutters quite obviously every second or so.