Firefox Task Manager extension

Martin Brinkmann
Sep 11, 2016
Updated • Jun 25, 2017
Firefox, Firefox add-ons

Task Manager is a brand new browser add-on for the Firefox web browser that adds task manager like capabilities to the Firefox browser.

One of the cooler things of Google Chrome is the Task Manager that Google ships with the browser natively.

Chrome's Task Manager displays all open websites in tabs, internal processes, and extensions, and lists their memory, cpu and network use.

You may use it to end any process right from there, which can be mighty helpful if a website or extension is misbehaving in one way or another.

To open the Task Manager in Chrome, simply use the keyboard shortcut Shift-Esc, or click on Menu > More Tools > Task Manager instead.

Firefox Task Manager

firefox task manager

The new Firefox add-on Task Manager works similarly. You need to install it first in Firefox though as it is a third-party add-on and not natively integrated in the browser.

The extension adds an icon to the main Firefox toolbar that you may click on to display the tasks in the browser.

Note: The author states that the extension works best if you have multi-process Firefox enabled. This test was done on a machine running Firefox with e10s and eight content processes enabled.

The Task Manager interface for Firefox opens in a new window when you click on it. The information it displays list the type of task (e.g. web page or add-on), a description which usually is a name or title, memory use, process ID and information, cpu and system utilization and P.Memory.

You may notice that memory is not listed for some tasks (usually not for add-ons or system).

A click on a task displays additional information about it in the lower pane. This includes its full url, if available, and various memory related information.

The extension refreshes the listing every 2 seconds by default which you can increase up to 10 seconds or decrease to 1 second. It would be handy if there was an option to pause the refreshing.

Just like Chrome's Task Manager, Task Manager for Firefox allows you to kill processes. All you need to do is select one or multiple processes -- there are checkboxes for that in the front of each line -- and click on the kill process button afterwards.

Please note that the ending of processes is limited to web pages currently. The "kill process" button remains inactive if you select system or add-on tasks in the listing.

A killed website is terminated immediately. This means that its tab is closed, and if it was the last tab of a window, that window enters Valhalla with it.

Closing Words

Mozilla incidentally is working on a feature to display the memory use of individual content processes as well in Firefox. Task Manager offers an advanced interface however and options to kill processes, something that Mozilla's current implementation does not support.

All in all, another shining example of how powerful Firefox's add-on engine is currently.

Now You: Do you monitor memory use of your browsers?

software image
Author Rating
4.5 based on 10 votes
Software Name
Task Manager
Software Category
Landing Page

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  1. Xircal said on September 12, 2016 at 6:43 pm


    The link in the Closing Words paragraph loads a blank page (?)

    1. Martin Brinkmann said on September 12, 2016 at 6:57 pm
  2. Atavic said on September 11, 2016 at 11:40 pm

    Point is: If you have a multi-process browser… only one single tab hangs, while the GUI doesn’t, so you can open up this extension and kill the hanged tab (aka the single process).

    1. Dan82 said on September 12, 2016 at 1:20 pm

      The question I posit to you in reply: why should you even need an extension for that? If you’re were to use a multi-process browser, the interface would not be affected by a frozen tab, so you should always be able to close the tab directly and achieve the same result. Any browser that doesn’t even offer this basic functionality is something to be avoided. I haven’t tried the Firefox e10s builds though, so I can’t comment on the quality of its multi-process design and user-friendliness.

      1. Martin Brinkmann said on September 12, 2016 at 2:05 pm

        I think the Task Manager in its current form is more about listing how much RAM each site uses. It would be more useful if you could kill plugins/add-ons as well, but that is not possible currently.

        Firefox’s interface is not super responsive if a site crashed, and that is only if the crash does not take the whole browser with it. This should not happen anymore with e10s but things can still lag or be really slow especially with only one content process currently.

        I did not run in crashes yet after enabling e10s, but will monitor the situation closely and report back on e10s effectiveness, or lack thereof, in this regard.

  3. Yuliya said on September 11, 2016 at 7:22 pm

    People use it? I consider myself fairly tech literate, but really only opened the task manager in Chromium so see how it looks like and then closed it. I assume it could be useful if one tab hangs, use it to kill that particular tab, but usually for me if one tab hangs the whole browser becomes unresponsive, or crashes. For what it is, it’s good nonetheless, like monitoring RAM usage of extensions..

  4. Dresandreal Sprinklehorn said on September 11, 2016 at 6:06 pm

    Working great in Firefox 48.0.2 64 bit with e10s activated in Windows 8.1.

    1. Liv said on September 11, 2016 at 6:24 pm

      Multi-process is also disabled in my Firefox 49.0b12 b4-bit on Arch Linux 64-Bit.

  5. Tom Hawack said on September 11, 2016 at 2:47 pm

    As the article states it, “The author states that the extension works best if you have multi-process Firefox enabled.”.

    Multi-process is not active on my Firefox 48.0.2 64-BIT with 70 add-ons on / Windows 7SP1 64-BIT (info for what it’s worth).

    The Firefox Task Manager extension here displays :

    – Memory only for webpages
    – Processes : same value for all, that of parent (logical since not multi-process)
    – CPU%, System%, Impact for all groups

    In fact, without Electrolysis activated Memory and Processes data lack. I’ll move to Electrolysis sooner or later, perhaps rather later if not when no choice simply because of 30+ add-ons among the 70 which are not at this time e10 compatible.

    1. Tonyt said on September 11, 2016 at 9:58 pm

      Tom, just curious, with 70 add-ons, do you find Firefox quite slow compared to Firefox without any add-ons? You can try Firefox without any add-ons for a moment by creating a new temporary Firefox profile.

      1. Tom Hawack said on September 11, 2016 at 11:39 pm

        The only issue I notice is the startup length, and it’s more related to maybe 6 specific add-ons than to the fact they are 70 all together. Surfing speed is not impacted, the overall velocity, page rendering, as the sum ProtectionExtraDelay – SkippedGainedDelay remains IMO < default settings, perhaps even < 0 (I gain more with the adequate add-ons allowing to skip connections (among which ads+tracking) then I lose time by using these add-ons). This equation includes 4-5 add-ons. The remaining add-ons are neutral when surfing.

        It's not the number of add-ons that counts, it's what each brings and takes specifically.

    2. Anonymous said on September 11, 2016 at 5:09 pm

      >70 add-ons

      WTF, man?

      1. Tom Hawack said on September 11, 2016 at 11:40 pm

        My harem, even if I have a trio of favorites :)

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