If you are thinking firefox has become slower and sluggish then these slow add-ons could be the reason behind it!
The official site says:
“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.”
The slowest add-ons on the list,Firebug, slows down Firefox’s startup by whopping 81%.The list of add-ons along with their degree of performance degradation is given below:
So,disable the add-ons which are of no use to you and enjoy faster browsing!