Firefox Feeling Sluggish? Disable Your Add-Ons


Firefox 4 included an update to its JavaScript engine, which made for some serious performance gains. Now Mozilla is going after another cause of sluggishness: slow start-up times caused by add-ons. If your install of Firefox feels slow to start up, you may want to try disabling some add-ons. According to Mozilla, on average, each add-on a user has installed adds 10 percent to Firefox’s start-up time. But that’s only for the average extension; some add-ons have a much worse start-up time impact than others.

To encourage add-on developers to consider this performance hit and optimize their add-ons, Mozilla has started testing the 100 most popular Firefox add-ons and releasing a weekly-updated list of their impact on browser start-up time. Here is a “rogue’s gallery” of the 10 add-ons with the worst impact on start-up time:

  1. FoxLingo – Translator / Dictionary
  2. Firebug
  3. AniWeather
  4. FlashGot
  5. FoxClocks
  6. FoxyTunes
  7. Video DownloadHelper
  8. FastestFox – Browse Faster
  9. Xmarks Sync
  10. SimilarWeb – Find the Best Sites on the Internet

The two worst-performing add-ons in the list, FoxLingo and Firebug, add a whopping 76 percent each to Firefox’s start-up time.

As well as publishing the slow add-ons list, Mozilla will also be adding warnings to the Add-On Gallery listing of any add-on that slows Firefox’s start-up time by 25 percent or more. The Mozilla effort to improve add-on performance is not just about “naming and shaming” poor performing add-ons, though,  Mozilla is also providing assistance to developers to optimize add-ons by updating its performance best practices documentation, and by releasing tools to help developers test their products.

The availability of a wide range of useful extensions is one of the reasons I use Firefox; I compiled a list of my favorites here. But Mozilla’s testing data shows that it’s good idea to regularly review the add-ons you have installed and disable those you no longer or rarely use, particularly if they appear on the list of the worst offenders above. Disabling an add-on stops Firefox from loading it, so it will no longer affect start-up time, but keeps the add-on in your add-on manager list so it can be re-enabled when you need it. Firebug, for example, is a really useful debugging tool, but I only use it very occasionally, so from now on I’m going to keep it disabled.

Photo courtesy Flickr user Photo Monkey


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