Finally a quantitative way to find out the culprits behind the Firefox slowdowns.
“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.”