While typing into the comment field on YouTube, the CPU usage is going ridiculously high (20% w/ a quad core CPU). Other users experienced slowdowns, too, when performing this action. I investigated the issue a little and found out that a script is responsible for this: http://s.ytimg.com/yt/jsbin/www-core-vfld_ifp8.js It's kinda big, but i hope someone can bisect it. STR: 1. Open any YouTube video, and log in to YT. 2. Start typing into the comment field under the video, and check out the CPU usage.
Created attachment 632138 [details] Deobfuscated core.js I checked the script w/ Firebug. While typing into to text field: Cd() : calls: 438 percentage: 35.24% Ra() : calls: 115121 percentage: 27.24% anonymous() : calls: 115121 percentage: 17.15% (La() ??)
I think I can reproduce this. On my machine, just watching the video, CPU usage is about 3-4%, and it goes up to 8% when I type (8-core, so it's still most of a core). In Chrome it's about 1% and goes up to 2% when typing. Do you know if this is a regression?
I experienced this bug during several months in the past. Typing slowed down and Firefox became unresponsive (with the error message 'Not Responding') and failed to write my entire comment. If I disabled HWA, it was pretty normal, so I think it was an issue with HWA (maybe GPU driver issue or bug in FF that's now fixed).
(In reply to David Mandelin from comment #2) > Do you know if this is a regression? I do not know, but i try to find out. Thanks for checking this bug! :) (In reply to Loic from comment #3) > and failed to write my entire comment. If I disabled HWA, it was pretty > normal, so I think it was an issue with HWA (maybe GPU driver issue or bug > in FF that's now fixed). No, this is not a HWA issue. I tried disabling everything, and definitely the script is the culprit.
Okay, i checked it. It's not a regression. I bisected w/ mozregression, and i can reproduce even in the 2007-05-01 Nightly... I did not go any further... :)
OK, it's not a regression then. Seems like more of a general perf issue, so I'm moving to that bucket, which is planned for a bit later.
Whiteboard: [js:p1:fx16] → [js:p2][js:bumped:1]
Whiteboard: [js:p2][js:bumped:1] → [js:p2][js:bumped:1] [platform-rel-Youtube]
2 years ago
platform-rel: ? → ---
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