I have a Linux desktop PC, and recently it has started "stalling" for (what feels like) ~200-500ms. This occurs every few minutes. If I'm (e.g.) watching a Youtube video, the video stalls, but the audio doesn't. It'll happen for other operations: it just happened while I was typing this post, in fact.

This is irritating. It also occasionally happens while playing Kerbal Space Program, and that could be fatal to my Kerbals.

Plus: it only just started happening (last couple of days), which makes me concerned that something expensive is on its way out.

Any ideas for Linux-y places I could look to see what's happening?