Sample page Rated 5 out of 5 stars

http://io9.com/5929783/jetpacks-voldemort-mary-poppins-the-most-ridiculous-fantasy+fueled-images-from-the-olympic-ceremony

I stand on its pages a few minutes and then I close all tabs. But the processor is busy on 40-50% until the browser is closed.

This review is for a previous version of the add-on (1.0.6). 

Thank you for the link. We will investigate this issue.

EDIT: We have just released v1.1.1 which reduces the CPU usage by this extension and improves the user experience.

Rated 5 out of 5 stars

Experimental version 1.0.7 also has a CPU-load bug. (FF 14.0.1)

This review is for a previous version of the add-on (1.0.6). 

Thank you for reporting this new issue. If you could point us to some page that you had experienced the CPU-load problem with the new experimental version 1.0.7, we would greatly appreciate it.