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Sometimes there's a nasty, guilty, CPU-hogging tab in Firefox that's maxing one of my CPU cores and making the whole browser sluggish. I'd like to find it and close it.

Sometimes I get lucky, but not often enough. So even the slightest hint of which tabs are most active would be a great help. (That is, even without a Chrome-like process-per-tab model or 'Task Manager', any idea that a particular tab is over-active would be appreciated. Is it using a lot of JS timers? Triggering a lot of events/invalidations? Etc.)

Already have removed Flash. Already run with NoScript (which usually helps but occasionally, its partial blocking of a page seems to trigger the busy-loops). Fingering the top memory-users via the "about:memory" report is slow, awkward, and doesn't quickly find the real culprit.

So: is there any other developer feature that could help? Or an add-in? Or a third-party tool (perhaps based on attaching to FF like a debugger) that can 'blame' a tab for whatever pointless spinning is happening?

(Looking for a way to finger the tab or tabs most likely to be responsible. Not interested in solutions that require a Firefox restart each time the problem recurs: that already works but loses too much loaded data.)

(APPEAL FOR REOPEN: By being more specific about things tried and non-responsive answers, this highly-findable question can draw more directly-responsive answers, like the about:performance answer hidden in @Thomee's comment and also at @fmt's answer on another question. Then as a true answer here, I could then 'accept' it for added findability. As it stands, the duplicate notice just points to yet another locked-as-duplicate question that also can't get the best current answer added/accepted.)

Community
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gojomo
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2 Answers2

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As you can see here it's on their list for 7 years.

Electrolysis is available in the nightly version roughly since the beginning of 2014, and that seem like the only possibility at the moment.

Marcus Müller
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EliadTech
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8

Via a suggestion from HN user ~liminal, a short sampling (~10 seconds) using the Developer Tools 'Profiler' might be helpful in such situations.

I've just tried this in Firefox 33.0, and many of the report-rows include a related source domain, which may help identify the tab responsible. (Unfortunately, many of the report-rows are related to domains like apis.google.com, which might be in use in any given tab.) Still, it's a start.

gojomo
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