>This extension hides private and important metadata of your browser, usually
obtainable using resource:// URIs, against the Web. You should have it
installed if you use many extensions, because having many extensions means
having many tracking and fingerprinting vectors. Also, Web sites can
generally probe Firefox for installed extensions in many cases without this.
Not, if you disable javascript. Almost all tracking techniques and the vast
majority of browser exploits do not work if you disable javascript.
If you really love privacy use the Tor Browser Bundle.