Without this add-on, Firefox has become an unwieldy, slowly dying wind bag. It will suck in 6GB of memory in a handful of hours, with heavy browser work. That's because of the tons of scripts and media being run on your computer. Even NoScript is not a good alternative, because it's very cumbersome - even if you use it for safety. Just be sure for ATD, that you spend a few minutes in OPTIONS (Tools / Plugins / ATD - Options) because you'll be consuming A LOT of bandwidth needlessly RELOADING stuff you're in the middle of. I am currently using 1,800 seconds before discard (30 min.), instead of the default 600 (10 minutes.)