Rated 3 out of 5 stars

I'd like to point out a fairly serious issue that should be easy to correct. You have listed the memory used by Firefox in Mb (megabits). The B should be capitalized.

Mb = Megabits (8Mb = 1MB)
MB = Megabytes

3 stars because it requires a restart. Chromium-based browsers allow you to free memory without restarting by use of the --purge-memory-button command line.

This review is for a previous version of the add-on (1.9.1-signed.1-signed).