Firefox Sends CPU to 100%

I was an early user of Firefox and continue to support the Open Source browser.  Last year my computer (Dell Latitude E6500 running Windows XP) began to have problems keeping up with Firefox.  I recognize that I have a lot of very useful Extensions and a good number of Add-ons and a few plugins.  However, seeing my CPU hit 100% on a regular basis became unacceptable. Firefox will have 50% or 60% of the total CPU and the laptop becomes unusable as it grinds to a halt. Power Off.

What’s the Cause

I have no idea yet.  My guess is that it may be something to do with Video, Anti-Virus or something installed on Firefox.


If I run TweetDeck (an Adobe Air application) along with Firefox 3.6 and then run Safari 5.0.3 and play something on Hulu (not full screen), eventually the CPU will hit 100%.  The interesting part is that even after Closing all three of these applications the CPU remains at 100%.  That is frustrating.

I Tried Chrome.

It was surprising to see how many plugins are available for Chrome. After installing a bunch I made Chrome the default browser.  But over time I didn’t like the way RoboForm is implemented and a few other Extensions that I missed made my daily browsing more difficult than it needed to be, so I reverted to Firefox.


Uninstalling AVG provided some relief.  I am still testing, but removing AVG seems to have eliminated the problem of the CPU staying at 100% even after closing the applications. Now, after closing the apps the CPU returns to a restful state.

Installed Firefox Extensions and Plugins

Do you know which Firefox Extensions might cause heavy CPU usage? Below is a list of everything installed on Firefox.
My Config- default

Generated: Sat Jan 08 2011 09:14:23 GMT-0500 (Eastern Standard Time)

User Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv: Gecko/20101203 Firefox/3.6.13 ( .NET CLR 3.5.30729)

Build ID: 20101203075014

Enabled Extensions: [41]

  • AI Roboform Toolbar for Firefox 6.10.1 – Allows the use of Roboform in Firefox.
  • ColorfulTabs 4.6.5 – Colorful Tabs colors every tab in a different color and makes them easy to distinguish while beautifying the overall appeal of the interface.
  • ColorZilla 2.2.2 – Advanced Eyedropper, ColorPicker, Page Zoomer and other colorful goodies
  • Domain Details 2.6.8 – Displays Server Type, Headers, IP Address, Location Flag, and links to Whois Reports
  • FEBE – Backup your Firefox data
  • Firebug 1.6.1 – Web Development Evolved.
  • FireFTP 1.0.10 – FTP Client for Mozilla Firefox.
  • Fission 1.0.9 – Progress bar in the address bar (Safari style).
  • Greasemonkey 0.8.20100408.6 – A User Script Manager for Firefox
  • Html Validator – Adds HTML validation to the View Page Source of the browser. The validation is done by Tidy from W3c.
  • Java Console 6.0.22
  • Java Console 6.0.23
  • Java Quick Starter 1.0
  • Link Diagnosis 1.2.2 – Examine link competition
  • LinkChecker 0.6.6 – Check the validity of links on any webpage.
  • LinkDiagnosis 2.2 2.2.41 – Examine link competition using the new and improved Link Diagnosis Tool
  • Live HTTP headers 0.16 – View HTTP headers of a page and while browsing.
  • MeasureIt 0.4.6 – Draw out a ruler to get the pixel width and height of any elements on a webpage.
  • Microsoft .NET Framework Assistant 1.2.1 – Adds ClickOnce support and the ability to report installed .NET Framework versions to the web server.
  • Move Media Player 7 – Media Player
  • Mozbar 0.51 – A toolbar for the users of, Inc.
  • MR Tech Toolkit 6.0.4 – MR Tech Toolkit power tools for all users. (en-US)
  • NewsFox 1.0.5 – RSS/Atom News Reader.
  • PDF Download – Allows you to choose what to do with a PDF file: download it, view it with an external viewer or view it as HTML.
  • RankChecker 1.7.9 – Track where your site ranks in Google, Yahoo, and Microsoft Live Search using the free Firefox rank checker.
  • Screengrab 0.96.3 – Saves a web-page as an image.
  • SearchStatus 1.33 – Display the Google, Alexa, Compete and Linkscape ranking with search-related tools.
  • SEO Blogger 1.0.4 – Wordtracker’s SEO Blogger extension
  • SEO Doctor 1.4 – Calculate link statistics of the current website
  • SEO For Firefox 3.4.2 – SEO information inline with Google and Yahoo! search results
  • SEO Link Analysis 1.0.7 – Adds display of PageRank, linktext and nofollow links to external links in Google Webmaster Tools and Yahoo! Site Explorer
  • Seo Toolbar 1.1.3 – The SEO Toolbar allows you to look at on page and off page competitive research details from the convenience of your Firefox browser as you browse the web. It also allows you to find keywords by putting many keyword tools at your fingertips. Have SEO questions? Ask them in the SEO Book Community Forums!
  • SEOpen 1.1 – Provides some basic tools to help with search engine optimization.
  • Session Manager – Saves and restores the state of all windows.
  • StumbleUpon 3.76 – StumbleUpon Toolbar
  • Tab Mix Plus – Tab browsing with an added boost.
  • Total Validator 6.9.1 – Validates web pages in numerous ways
  • Update Notifier – Notifies you when updates are available for your extensions and themes.
  • Web Developer 1.1.9 – Adds a menu and a toolbar with various web developer tools.
  • Website Health Check Tool 1.1.3 – The Website Health Check tool aims to provide a simple and intuitive interface to seeing if your site has any major SEO issues.
  • YSlow 2.1.0 – Make your pages faster with Yahoo!’s page performance tool

Disabled Extensions: [7]

  • After the Deadline 1.50 – After the Deadline checks spelling, grammar, and style in your web forms.
  • BlekkoToolbar 1.0.2 – Blekko’s Search Toolbar
  • Ghostery 2.4.2 – Ghostery identifies and allows you to block the 3rd parties (web bugs) that are hidden on the current page you’re visiting. Web bugs include ad networks, behavioral data collectors and web analytics providers.
  • HP Smart Web Printing 4.60 – Print what you want, how you want.
  • SeoQuake 2.6.8 – Quick view of site parameters in the search engine results pages.
  • SeoQuake Plugin – 1.0.6 – SeoQuake Plugin –
  • Speed Dial – Direct access to your most visited websites

Total Extensions: 48

Installed Themes: [1]

Installed Plugins: (28)

  • 2007 Microsoft Office system: NPOFF12.DLL- Office Plugin for Netscape Navigator
  • Adobe Acrobat: nppdf32.dll- Adobe PDF Plug-In For Firefox and Netscape “9.4.1″
  • downloadUpdater: npdnu.dll- npdnu
  • downloadUpdater2: npdnupdater2.dll- npdnupdater2
  • Google Talk Plugin: npgoogletalk.dll- Version
  • Google Talk Plugin Video Accelerator: npgtpo3dautoplugin.dll- Google Talk Plugin Video Accelerator version:
  • Google Update: npGoogleOneClick8.dll- Google Update
  • iTunes Application Detector: npitunes.dll- iTunes Detector Plug-in
  • Java Deployment Toolkit npdeployJava1.dll- NPRuntime Script Plug-in Library for Java(TM) Deploy
  • Java(TM) Platform SE 6 U23: npjp2.dll- Next Generation Java Plug-in 1.6.0_23 for Mozilla browsers
  • Microsoft® DRM: npdrmv2.dll- DRM Netscape Network Object
  • Microsoft® DRM: npwmsdrm.dll- DRM Store Netscape Plugin
  • Move Streaming Media Player: npqmp071500000347.dll- npmnqmp 989898989877
  • Mozilla Default Plug-in: npnul32.dll- Default Plug-in
  • QuickTime Plug-in 7.6.9: npqtplugin.dll- The QuickTime Plugin allows you to view a wide variety of multimedia content in Web pages. For more information, visit the QuickTime Web site.
  • QuickTime Plug-in 7.6.9: npqtplugin2.dll- The QuickTime Plugin allows you to view a wide variety of multimedia content in Web pages. For more information, visit the QuickTime Web site.
  • QuickTime Plug-in 7.6.9: npqtplugin3.dll- The QuickTime Plugin allows you to view a wide variety of multimedia content in Web pages. For more information, visit the QuickTime Web site.
  • QuickTime Plug-in 7.6.9: npqtplugin4.dll- The QuickTime Plugin allows you to view a wide variety of multimedia content in Web pages. For more information, visit the QuickTime Web site.
  • QuickTime Plug-in 7.6.9: npqtplugin5.dll- The QuickTime Plugin allows you to view a wide variety of multimedia content in Web pages. For more information, visit the QuickTime Web site.
  • QuickTime Plug-in 7.6.9: npqtplugin6.dll- The QuickTime Plugin allows you to view a wide variety of multimedia content in Web pages. For more information, visit the QuickTime Web site.
  • QuickTime Plug-in 7.6.9: npqtplugin7.dll- The QuickTime Plugin allows you to view a wide variety of multimedia content in Web pages. For more information, visit the QuickTime Web site.
  • RockMelt Update: npRockMeltOneClick8.dll- RockMelt Update
  • Shockwave Flash: NPSWF32.dll- Shockwave Flash 10.1 r102
  • Silverlight Plug-In: npctrl.dll- 4.0.51204.0
  • Turner Media Plugin NPTURNMED.dll- NPTURNMED
  • Unity Player: npUnity3D32.dll- Unity Player 2.6.1f3
  • Windows Media Player Plug-in Dynamic Link Library: npdsplay.dll- Npdsplay dll
  • Windows Presentation Foundation: NPWPF.dll- Windows Presentation Foundation (WPF) plug-in for Mozilla browsers

I welcome all suggestions leading to a resolution of this issue.  Well, except the constant refrain from my friends to buy a Mac, unless of course you want to Chip-In. This is for you Phil and Chris and many others!!! :-P

But, I digress.  I really want to get Firefox running in a stable manner again.  I think that removing AVG was a help, but it is not the solution.  I will add notes here as various solutions are tested and proven effective or not.

All suggestions are welcome int the comment area below.

UPDATE: In a new post I describe how I have created a new installation of Firefox using PortableApps.

UPDATE 2: The version of RoboForm was giving errors. I upgraded RoboForm and I am no logger getting a script error. Removing Tab Mix Plus may also have beneficial.   I also switched from AVG to Avira anti-virus program.  I have TweetDeck, PortableApps Firefox and Hulu playing on Safari and things are running well so far.


10 Responses to “Firefox Sends CPU to 100%”

  1. Chris Lackey Says:

    I didn’t think of this before, but I’d actually suggest upgrading to Windows 7. It’s solid, secure, and speedy.

  2. cchrissyy Says:

    I’ve had the very same issue for a long time, but today I was able to fix it instantly by simply disabling the Web Developer Toolbar.

    pffff. I’ll miss it!

  3. @kennyhyder http://www.jbspart… Says:

    [...] scroll down near the bottom to Mac Book [...]

  4. Andrew Burnett Says:

    Well, Jim, I came here to contribute and ‘Chipin’ in accordance with your tweet, but somehow the ‘chipin’ button isn’t showing on the iPad… so, in echange for telling you to “get a mac” I will send you a mac mouse once you’ve got it :)

  5. Jim Spencer Says:

    Aw, come on. The thing must be built in Flash. I just can’t win!!! Have you seen the new Magic Mouse? Pretty amazing mouse.
    By the way. Go to your computer and try again.

  6. Alexey Says:

    Just uninstall Roboform and try again
    I think this is main trouble of your 100% CPU of Firefox
    I had same trouble in many my computers and always this is trouble of Roboform
    But you need to uninstall roboform (not turn off – this doesn’t help)

  7. dailor Says:

    Like @cchrissyy said: “… fix it instantly by simply disabling the Web Developer Toolbar.”

    I had same issue long time ago, and simply disabled all add-ins. Enabling them one-by-one, point me the “Web Developer Toolbar” as only perpetrator of that highly abnormal levels of CPU usage.

    PC: CPU Intel P4 3.0GHz HT, RAM 2.5GB DDR400
    OS: Win XP SP3
    Browser: Mozilla Firefox 4.x.x
    Web Developer Toolbar v1.1.9

  8. dailor Says:

    Now the “Web Developer Toolbar” Extension works much better with Mozilla Firefox 6.0 (Same PC/OS configuration). But Roboform v7+, cause very laggy experience both with FF5 & FF6.

  9. Mike Says:

    I had a similar problem several months ago. I don’t know how familiar you are with computers but, I will tell you what I did. Go to start and type in “msconfig” into the search box then hit enter. The system configuration window should pop up. Go to the Startup tab and click. Check all of the programs that are starting up with windows and make sure that there is not anything you do not want or need to run on Startup and uncheck the box. Sometimes a lot of programs startup that you don’t need to have running with the basic windows system. Only uncheck the items you know about and are sure you don’t need them on startup. Most of the items need to be running for windows to work properly. Most of the added on software that you installed on your computer does not need to been running normally. You also can click the services tab and do the same thing. Do not un-check anything if you are not sure, however you can always recheck it if some program does not work after changing it. Un-checking them does not delete them it is just disabling them on startup. This effects the memory and resources which will cause it to have a high CPU usage window pop up. My Norton Antivirus programs monitors this and brings up a window and logs it if when it happens. Since I removed about 6 items that were running on startup I have only had the problem 1 or 2 times in the last few months. Before I was having it happen whenever I started up several programs at once and was tabbing between them. It happened about 12 to 15 times a month. Good luck and if you are smarter than me you probably didn’t need this info. If you do have any other questions fill free to e-mail me.

    Mike, Arizona.

  10. Matthew Says:

    Hi, I had this problem, and on a hunch disabled and then removed the InvisibleHand add-on. Presto, no CPU max out, no fan blasting all the time!
    My suggestion: Check your Firefox add-ons. Some of them are very greedy resource hogs.

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