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There are times when the firefox responds reluctantly. And it is not only when i have opened many tabs. But there are cases when i have opened as many as 20 tabs and firefox is working fine and there are chances when i have opened just 5-6 tabs and firefox behaves lazy.
So, i guess it do not depend on number of tabs and there must be any specific tab which causes the problem.
Isn't there a way to find that tab out and close only that instead of closing complete firefox? Is there any addon for that, or any script?

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marked as duplicate by fixer1234, DavidPostill, nc4pk, mdpc, Ben N Jan 27 at 1:45

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.

This isn't a duplicate as this asks about CPU and memory (the linked to question just asks about CPU). For CPU go to the page about:performance , for memory go to the page about:memory. – Matthew Wilcoxson Jul 11 at 10:48
up vote 5 down vote accepted

The BarTab extension for Firefox might be useful for improving the situation :

BarTab can intercept when tabs are loaded in the background or restored after a browser restart and will only load the content when the tab is actually visited. It also allows you to free memory by unloading already loaded tabs, either manually or automatically.

Otherwise, you might switch temporarily to Google Chrome, where shift-esc displays the per-tab usage:


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BarTab seems promising. I don't use Chrome as it is not having those addons which i like. – Rakesh Juyal Apr 1 '11 at 6:47
Please note: Not currently available for Firefox 11.0 – Nathan Koop Apr 13 '12 at 18:31
@NathanKoop: FF compatibility has become rather meaningless with the current version speedup. I use the Add-on Compatibility Reporter to untangle the mess. – harrymc Apr 13 '12 at 18:42
2… - works for 17.01 – Enigma Mar 1 '13 at 18:18
Not available in Firefox 40. – Ricardo Martins Aug 19 '15 at 0:01

Opening the browser to about:memory can show per-tab memory usage.

further reading

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For Firefox, I've made an addon which displays tab memory usage in the corresponding tab's title.

Provides user with tab related stats and memory usage ..



  • How many tabs are currently open
  • How many tabs have been opened during this Firefox session
  • How many tabs have been opened since addon installed
  • Display tab memory usage in title
  • Preference to toggle tab memory usage on/off
  • Preference to set interval between memory usage collection
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Do you know ANY way to find out even a hint as to which TAB (or even relevant URL) is eating CPU? – tbone Mar 15 '15 at 17:54
Afraid I don't at the moment, but once I find out I plan on including that data in the addon too. – bobbyrne01 Mar 18 '15 at 17:56
I'll ask since you may have the knowledge....these various addons that "unload" tabs - in my experience, they seem to visually unload them, but Firefox doesn't give up any of that memory; or, when you restart Firefox, it seems to eat all of the memory required for the opened tabs, even before you click on each one and it loads (implying they are being physically loaded in the background, but not displayed). Would you happen to know if this IS in fact the situation? – tbone Mar 18 '15 at 20:28
@bobbyrne01 I am using your addon right now! Good stuff. – AntonioCS Sep 27 '15 at 21:47
@tbone Firefox doesn't give up any of that memory: Unless each tab is running in a separate process, I suspect this is a limitation of the operating system's memory management in that it won't "give back" the memory it uses (depends upon the operating system of course and also how Firefox itself handles memory). Check the Electrolysis wiki page: Theory: If I am using Electrolysis, and I close a tab, I believe that should terminate the separate operating system "process" that houses that tab and its consumed memory. – bgoodr Mar 12 at 18:18

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