Seems like a while slew of issues. On first run I noticed how scroll FPS are killed by video loading. Second load had a massive hang during page load that froze the video. A network issue is that the tab throbber takes forever to stop. Always everything (other than the giant videos) is loaded right away. Quantum Network should be interesting here, to de-prioritize off screen items. Testing in Chrome, the video shortcuts the scrolling issue by pausing the video during scroll.

A profile that includes page load and sluggish scrolling: https://perfht.ml/2ohUSYt

ni? bas, Anthony mentioned there might be fixes in the works.

As far as I can tell this is just video decoding stealing all of the system's bandwidth and making it impossible for the GPU to get any compositions done. I don't see anything in the graphics realm we can do here. The media guys are looking into shutting down or pausing video decoding for non-visible videos like we do with background tabs as far as I understood it from Anthony.

(In reply to Bas Schouten (:bas.schouten) from comment #3) > The media guys are looking into shutting down or pausing video > decoding for non-visible videos like we do with background tabs as far as I > understood it from Anthony. Is this ^^ work tracked in a bug somewhere? (which this bug could be marked as depending on, perhaps)