Tweaking Firefox – the best solution
Firefox is one of the most extensible and tweakable browsers in the world, which makes it possible to increase the privacy in Firefox considerably by using different configurations and tweaks without having to patch the source code. And this is one of the things that makes Firefox really great. Generally Firefox as a product is not the problem, the Mozilla Foundation is. When you tweak Firefox you not only run with the latest version of Firefox, but you also get a true privacy-respecting browser.
Firefox is unique in this way as no other browser, as far as I know, allows for so much tweaking without patching. Tweaks are settings that control Firefox’s behavior. Some can be set from the options interface, which can be in
about:config, but others are called „hidden preferences“ which will only show when they are set by the user.
Tweaking Firefox is not for everyone however. It requires you to spend time studying the different settings you can manipulate and understanding how they work. But your not alone, many people do this, and one of the best ways to do it is to use the Arkenfox user.js project as a template. One of the benefits of tweaking Firefox is that you get to better understand what exactly your browser is doing and how it works.
The „Arkenfox user.js“ project provides a comprehensive
user.js template for configuration and hardening Firefox. It is very actively maintained by some very skillful people, including an active Mozilla developer and a developer from the Tor project.
user.js is very well documented, but if you feel the need for a guide I recommend you take a look at The Firefox Privacy Guide for Dummies!