YouTube is causing widespread browser slowdowns due to a suspected interface bug that triggers an endless layout loop. Users across Firefox, Brave, and Edge report heavy lag, stuttering, and RAM usage exceeding 7GB in some cases. According to a report, the issue lies in YouTube’s flexible menu below the video player. The interface repeatedly hides and restores buttons, forcing constant layout recalculations. This loop consumes CPU and memory, leading to freezing tabs. Mozilla is investigating, but no fix has been confirmed yet.