Without a variety of extensions, the Firefox browser is difficult to achieve today's situation, but while adding powerful features, there are also a lot of extensions that directly slow down Firefox's running speed, some even make it completely unable to access the Internet.
If you think there may be extensions that have slowed down Firefox, you may as well look at the top 10 killers officially announced by Mozilla,The following percentage number indicates the slowdown caused by installation..
1. FoxLingo-Translator/Dictionary 74%
2. Firebug 74%.
3. AniWeather 54%
4. FlashGot 50%
5. FoxClocks 46%
6. FoxyTunes 44%
7. Video DownloadHelper 33%
8. FastestFox-Browse Faster 33%
9. Xmarks Sync 30%
10. SimilarWeb-Find the Best Sites on the Internet 23%
Mozilla also reminds Firefox users that to achieve the best performance,Disable unnecessary extensions.And temporarily enable it when necessary.