Firefox is very slow at Fedex.com

Show proof of the issue. Here is the add-on I use to see the load time. https://addons.mozilla.org/en-US/firefox/addon/load-time/ Who are you using for DNS on you computer, browser, and router? Are you running any security software besides MS Defender? Windows home or pro? Have you tried with Firefox in Troubleshoot Mode? https://support.mozilla.org/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode#w_how-to-start-firefox-in-4troubleshoot-modesf5safe-modesf Did you clear your browser cache? https://support.mozilla.org/en-US/kb/clear-cookies-and-site-data-firefox