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:
- FoxLingo – Translator / Dictionary
- Video DownloadHelper
- FastestFox – Browse Faster
- Xmarks Sync
- 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.