Rated 4 out of 5 stars

Great stuff! However, here is a problem I had:
On my Firefox 23.0, running under Ubuntu 13.04, the add on keeps firefox CPU usage at ~20%, even when showing an arbitrary page. If I disable the ad-on, firefox CPU usage is close to zero.

This review is for a previous version of the add-on (2.1.5.1-signed).