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I often have many Firefox windows open, each with many tabs.

Now and then one of the tabs will be running a web page that for some reason consumes lots of resources. Right now, I have a tab somewhere that is constantly consuming 10% of the CPU...which would be fine as my computer can easily handle that (see specs below...all other apps are responsive), but it seems to slow Firefox down....everything, everywhere is extremely laggy in Firefox, I can see pauses while I type this.

Is there: - a way I can isolate separate instances (or even tabs) in FF into a separate process, so one rogue tab doesn't bog down FF across the entire system? - maybe an add-in that can either identify tabs consuming lots of CPU, or maybe a way to "shut down" activity on tabs you haven't used in a while?

Firefox 3.6.10 Windows 7 Ultimate 64 i7 920 @ 3.6 GHz 12 GB Ram

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marked as duplicate by slhck Mar 2 '13 at 9:53

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

I would look for the tab running Adobe Flash and kill it, to see if that fixes the problem. – user3463 Oct 1 '10 at 5:51
Google Chrome separates tabs into separate processes, just like you described. Firefox doesn't do this because its developers view the trade off as too costly. You could try to identify it by opening the exact same set of tabs in Chrome (but a page that's problematic in Firefox won't necessarily be that way in Chrome). See also Firefox Support: Firefox consumes a lot of CPU resources. – Firefeather Jan 27 '11 at 20:08
Maybe it's a tab, maybe it's an addon. If it's a tab, how to check which one? Install noscript addon, disable scripts globally and then re-enable them one tab at a time. – Toc Mar 2 '11 at 12:22

I often have many Firefox windows open, each with many tabs.

It's normal behavior to have some CPU (and a lot of memory) usage when having a lot of tabs...

If you suspect too much, check for dynamic content on the web page, whether it's Javascript, Java or Flash.

Some examples:

  • Advertisements
  • Animations
  • Auto-refreshing behavior
  • Chat message queries
  • Multimedia
  • Tickers
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"check for dynamic content on the web page" - ya, but which of the 100 pages do I check is the question? – tbone Mar 16 '11 at 11:50
@tbone: All of them! But really, why run so many? 10% / 100 = 0.1% each, it's normal behavior. – Tom Wijsman Mar 16 '11 at 12:23

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