Firefox playing videos takes too much CPU

[Jan Beich]

"Mikhail T." <mi+t at aldan.algebra.com> writes:

> Hello! I noticed recently, how much CPU playing a video takes... A
> firefox-process, playing a modest 1080p clip (such as this 
> <https://www.youtube.com/watch?v=DrJY_-BIasY>) for example, will show
> in top as taking between 150-160% CPU (and mine are E5-1620 0 @
> 3.60GHz), with Xorg taking /another/ 30%. If I pause the video,
> CPU-usage drops down to single-digits, so it definitely is the
> playback...

Try profiling e.g., "pmcstat -t firefox -P instructions -T".

> If I download that same video (using youtube-dl), and give it to
> mplayer, the playback will only cost about 60% CPU for the mplayer 
> itself -- plus 20% for the Xorg. Mplayer using the simple "x11"
> video-output, nothing particularly fancy. The video card is an old 
> Radeon (5670/5690/5730).
>
> Is there a good explanation for this discrepancy? Thank you! Yours,

Maybe https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=203732