From Fedora Project Wiki

Slowness when browsing?

  • Sometimes your loaded extensions cause your browsing to be slow. Disable them and see if performance improves.
  • Many of these reference user.js [2] but you can use the about:config url as well if you prefer. Using user.js is preferable because Mozilla will not change these settings on your behalf, and you can easily undo them if something goes awry.
  • Cleanly exit your browser. Go to your profile folder [3]and vacuum your db files
cd $HOME/.mozilla/firefox/*/; for i in *.sqlite; do echo "VACUUM;" | sqlite3 $i ; done
  • Disable favicon and site-icon caching. Append do your user.js file: [4] [5]
user_pref("", false);
user_pref("", false);
  • Turn off IPv6. Append to your user.js file: [6]
user_pref("network.dns.disableIPv6", true);
  • Disable dbus notifications within Firefox. Append to your user.js file: [7]
user_pref("toolkit.networkmanager.disable", true);
  • Turn off rich colour support. Append to user.js: [8]
user_pref("gfx.color_management.enabled", false);
user_pref("gfx.color_management.mode", 0);
  • Turn off paint delay. Append to user.js: [9]
user_pref("nglayout.initialpaint.delay", 0);
user_pref("browser.cache.disk.enable", false);
user_pref("browser.cache.disk.capacity", 0);
user_pref("browser.cache.offline.enable", false);
user_pref("browser.cache.memory.enable", true);

Useful usability options

  • Enable form colours. Append to user.js: [14]
user_pref("browser.display.use_focus_colors", true);
user_pref("browser.display.focus_text_color", "#010101");
  • Disable blink tag. Append to user.js: [15]
user_pref("browser.blink_allowed", false);