This add-on is amazing! I use a lot of older computers, and run FireFox, as it is the fastest in my experience. The problem with it, is FireFox has no built in ad blocker, and ads can bring a computer to a crawl, especially an old one. This add-on does an amazing job at blocking resource hogging ads ad and pop-ups. I wrote this review on a 14 year old Dell laptop that can still surf the web thanks to this add-on!