Hello, When I try to play a 4K Video on YouTube on Firefox 88.0, it's choppy while the same video on YouTube on Microsoft Edge is smooth. From my understanding is doesn't seem to be related to my internet connection (Optic Fiber Orange / 300 Mbps) otherwise it wouldn't be smooth on Microsoft Edge nor to my hardware. A strange behavior of Firefox is that when I enter the address of the 4K Video, YouTube on Firefox doesn't automaticaly detect the 4K quality. Its auto-detection don't go above HD (1080p or 1440p) I have to manually change the quality and when I choose 4K it's choppy. The red playing bar is always closed to the grey "download" bar. If after selecting manually 4K quality, I select Auto quality again, YouTube on Firefox downgrade the video quality to 1440p. For the same video on YouTube on Microsoft Edge, when I enter the address of the video, auto-detection automatically goes to 4K and everything is ok. (The grey download bar is always far away the red playing bar) I don't think my hardware is faulty in term of power. CPU : Ryzen 5900 GPU : RTX 3080 Screen : Dual Screen with 4K Monitor (XV273K and XB271HK) Windows Version : 19042.928 (20H2) Firefox : 88.0 Graphic Drivers : Geforce Game Ready Driver 466.11 Could you help me to fix this, please? Thanks,