The article, Firefox Configuration Guide for Privacy Freaks and Performance Buffs, has heavily been updated with new information while other parts were edited to bring the information up to date. The most important changes include the addition of two sections, one dealing with how to sanitize the default search engines that ship with Firefox and another which details how to remove unwanted system add-ons which are packaged with the browser and install themselves without prompting the user.
I am currently testing Waterfox with the guide and so far, so good. Waterfox is a 64 bit web browser for Linux, Mac and Windows that, though based on Firefox, is more privacy-centric than Firefox. Its features include the removal of Telemetry and Pocket, as well as other methods which collect user data.