Are you running pro or home version of Windows? If pro, you should have sandbox enabled for testing. https://www.howtogeek.com/399290/how-to-use-windows-10s-new-sandbox-to-safely-test-apps/ Can you show the issue? see screenshot Here is the add-on I'm using to show load time. https://addons.mozilla.org/en-US/firefox/addon/load-time/ Who are you using for DNS?

You can create a new profile as a quick test to see if your current profile is causing the problem. See "Creating a profile": *https://support.mozilla.org/en-US/kb/profile-manager-create-remove-switch-firefox-profiles If the new profile works, you can transfer files from a previously used profile to the new profile, but be careful not to copy corrupted files to avoid carrying over problems. *https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile You can do a malware scan, just to be sure. *https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-caused-malware Boot the computer in Windows Safe Mode with network support to see if that has effect. *[https://www.bleepingcomputer.com/tutorials/how-to-start-windows-in-safe-mode/] *[https://www.digitalcitizen.life/4-ways-boot-safe-mode-windows-10/]