Always remember to run the 'ghacks' prefsCleaner script after every update to either their user.js or my user-overrides.js.
On rather important thing i added to my user-overrides.js is the following comment:
* ALWAYS READ THE 'LATEST CHANGES' SECTION NEAR THE TOP and if there are any * preferences in it that have been removed, these preferences need to be reset * from about:config in Firefox
If you really want to be sure any old prefs or incorrect pref values are removed from prefs.js, exit Firefox and rename it to prefs.js.bak, then restart Firefox.
Recent changes as follows:
* added 'webgl.dxgl.enabled' * added 'browser.newtabpage.activity-stream.asrouter.userprefs.cfr.addons' * removed 'browser.newtabpage.activity-stream.asrouter.userprefs.cfr' - depreciated * moved 'browser.display.use_document_fonts' to ghacks diffs section * moved 'layout.css.font-loading-api.enabled' to personal prefs section * minor edits