SourceSlow Performing Add-ons
Add-ons provide many useful features and functions, but they can also cause Firefox to become slower. Some add-ons can even slow Firefox to a crawl and make it difficult to use for regular web browsing. If you think add-ons might be the reason Firefox is lethargic, check the list below for some of the biggest bottlenecks. And remember, for best performance you should disable add-ons that you no longer use regularly.
Add-ons with Slowest Start-up
The following add-ons have the most impact on how long it takes Firefox to start up.
Rank Add-on Impact Longer lines are slower
#1FoxLingo - Translator / Dictionary by Linkular LLC
#2Firebug by Joe Hewitt, johnjbarton, robcee, FirebugWorkingGroup, Jan Odvarko
#3AniWeather by AniWeather