Why does the video start to slow down when watching on YouTube?

Question

YouTube

Hello, I began to notice the following, I watch a video on YouTube, and after 5 seconds it starts to play more slowly, that is, as if the frame rate drops, not like a slide of pictures, but still noticeable. And here's something else that I noticed interesting, as soon as I move the mouse, that is, just pull it from a state of rest without clicking on anything, the video starts playing again as it should, but as soon as I leave the mouse alone, it again starts noticeably slow down. With what it can be connected? I reinstalled flash player, didn't help. Then I read that this player is installed by default in chrome, so I removed it from the PC, rebooted the computer, but it still did not help. It's like this, I don't know what to do with it.

Answer 1

Look for the culprit by elimination.
First browsers, then OS. You can run linux in live mode. It's easy for some browser add-ons or other software to interfere.