See: *https://support.mozilla.org/kb/firefox-health-report-says-your-browser-is-slow Try to update to Firefox 29 via Help > About or download and save the full Firefox installer to the desktop and start the installation with a double-click on the desktop icon. You can find the full version of the current Firefox 29.0 release in all languages and for all Operating Systems here: *http://www.mozilla.org/en-US/firefox/all.html ---- It is possible that your security software (firewall, anti-virus) blocks or restricts Firefox or the plugin-container process without informing you, possibly after detecting changes (update) to the Firefox program. Remove all rules for Firefox and the plugin-container from the permissions list in the firewall and let your firewall ask again for permission to get full, unrestricted, access to internet for Firefox and the plugin-container process and the updater process. See: *https://support.mozilla.org/kb/Server+not+found *https://support.mozilla.org/kb/Firewalls *https://support.mozilla.org/kb/fix-problems-connecting-websites-after-updating ----- See: *https://support.mozilla.org/kb/reset-firefox-easily-fix-most-problems When you reset Firefox then a new profile is created and some personal data (bookmarks, history, cookies, passwords, form data) is automatically imported and the current profile folder will be moved to the desktop to an "Old Firefox Data" folder. Installed extensions and other customizations (toolbars, prefs) that you have made are lost and need to be redone. It is possible to recover more data from the old profile, but be cautious not to copy corrupted files to avoid carrying over the problem *https://support.mozilla.org/kb/Recovering+important+data+from+an+old+profile