http://www.askvg.com/ultimate-collection-of-best-aboutconfig-tweaks-for-mozilla-firefox-4-0/
user_pref("browser.allTabs.previews", true);
user_pref("browser.ctrlTab.previews", true);
user_pref("browser.download.manager.scanWhenDone", false);
user_pref("browser.fullscreen.autohide", false);
user_pref("browser.fullscreen.animateUp", 0);
user_pref("browser.panorama.animate_zoom", false);
user_pref("browser.preferences.animateFadeIn", true);
user_pref("browser.showQuitWarning", true);
user_pref("browser.tabs.animate", false);
user_pref("browser.tabs.closeWindowWithLastTab", false);
user_pref("browser.tabs.insertRelatedAfterCurrent", false);
user_pref("browser.urlbar.clickSelectsAll", false);
user_pref("browser.urlbar.doubleClickSelectsAll", true);
user_pref("layout.spellcheckDefault", 2);
user_pref("ui.click_hold_context_menus", true);
user_pref("browser.preferences.instantApply", true);
user_pref("browser.tabs.drawInTitlebar", false);
user_pref("middlemouse.paste", true);
user_pref("browser.urlbar.formatting.enabled", false);
user_pref("browser.urlbar.trimURLs", false);
user_pref("security.dialog_enable_delay", 0);
http://www.pcworld.com/article/171196/pimp_my_browser_how_to_get_the_most_out_of_firefox.html
user_pref("browser.sessionstore.interval", 30000) ; //default: 10000 (10sec)
user_pref("security.dialog_enable_delay", 0); //Add-on installation delay. defaults: 200
user_pref("browser.download.manager.openDelay", 3000); //supress dialog for very small downloads
user_pref("browse.search.openintab", true); //default: false
http://maketecheasier.com/28-coolest-firefox-aboutconfig-tricks/2008/08/21
//UI
user_pref("browser.urlbar.maxRichResults", 20); //default: 12
user_pref("gfx.color_management.enabled", true); //enable advanced color profile for displaying higher image quality
user_pref("browser.download.manager.scanWhenDone", false); //antivirus scanning
user_pref("browser.tabs.tabMinWidth", 30); //default: 100, I don't like scrolling
user_pref("browser.tabs.closeButtons", 1); //0: on active tab, 1: on all tabs, 2: no close button, 3: at end of tab bar
user_pref("browser.link.open_newwindow.restriction", 2); //js popups: 0: follow firefox new window settings, 1: no new window, 2:first js then firefox
user_pref("layout.spellcheckDefault", 0); //default 1: multi-line text boxes only //0:disable, 2:enable on all text boxes
user_pref("browser.fullscreen.autohide", false); //default:true
//performace
user_pref("config.trim_on_minimize", true); //dump memory to swap
user_pref("network.http.pipelining", true);
user_pref("network.http.proxy.pipelining", true)
user_pref("network.http.pipelining.maxrequests", 6); //default: 4, should be not more than 8
user_pref("network.http.max-connections", 45); //default: 30
user_pref("network.http.max-connections-per-server", 15); //default:15
user_pref("browser.cache.disk.enabled", true);
user_pref("browser.cache.disk.capacity", 1048576); //in bytes
user_pref("browser.cache.offline.capacity", 2048000); //offline cache, default: 512000(kb)
//addons
user_pref("security.dialog_enable_delay", 0); //Add-on installation delay. defaults: 2000(msec)
user_pref("extensions.getAddons.maxResults", 10); //defaults: 5, show more search result
user_pref("extensions.checkCompatibility", false);
user_pref("extensions.checkCompatibility.5.0", false);
user_pref("extensions.checkUpdateSecurity", false);
//misc
user_pref("browser.zoom.siteSpecific", false); //defaults: true
user_pref("view_source.editor.external", true);
user_pref("view_source.editor.path", "c:/windows/notepad2.exe");
// prevent firefox hidding 'http://' in URL
user_pref("browser.urlbar.trimURLs", false);