Fixing Firefox

    Disable and/or delete useless plugins:
    Disable: Firefox > Add-ons > Plugins > Disable
    Delete: Right-click plugin > Show More > "File" (find and delete)
    PROTIP: Disable Flash; enable YouTube HTML5: youtube.com/html5


    Restart Firefox in Safe Mode (addons disabled, default theme, default toolbar settings):
    Firefox > Help > Restart with Add-ons Disabled

    Reset Firefox to its default state:
    Firefox > Help > Troubleshooting Information > Reset Firefox

    Create a new profile:
    Run: firefox.exe -p
    Terminal: firefox -p

about: pages

Firefox command line (shift+F2)

    Save a PNG image of the entire web page:
    screenshot --fullpage

    Save a PNG image of the visible window only:
    screenshot

    Restart the browser:
    restart

    Show all of the available commands:
    help

userChrome.css or Stylish tweaks (tiny.cc/userchrome)

    /* No Firefox Button */
    #appmenu-button{display:none !important;}

    /* No load progress indicator */
    .tab-throbber{display:none !important;}

    /* No horizontal scrollbar */
    #content browser{margin-right:-14px !important;
    overflow-y:scroll; overflow-x:hidden;}

    /* No site favicon */
    .tab-icon-image{display:none !important;}

    /* No "X" button to close tab */
    .tab-close-button{display:none !important;}

    /* No auto-complete arrow on location bar */
    .autocomplete-history-dropmarker{display: none !important;}

    /* See http://p.pomf.se/483 for Menu Context removals */

    /* To make your own userChrome.css tweaks, find elements using the DOM Inspector on "chrome://browser/content/browser.xul" */