I've had this issue for years, but it was always something I could live with. The Issue would only appear once every week or so. However, recently the issue seems basically happen on a daily basis. After Firefox has been running for some time and there's a few other tabs open, The YouTube UI will periodically become completely unresponsive. Just moving the cursor on top of Youtube will cause 100% + CPU in the Firefox task manager and the page is entirely unresponsive during that time (except video playback)... This issue has persisted through reinstalls, new profiles and is also present without extensions. This is a performance Profile of the Issue: https://share.firefox.dev/4kNlhKD Any tips on how to maybe diagnose this are very much appreciated!