Please ensure that your internet connection is fast enough. If you are attempting to load a website, Firefox may cause other internet activities like videos to freeze.

There are also a number of other factors to consider, all of which are outlined in these basic Mozilla troubleshooting articles:

• Quick fixes if your Firefox slows down
• Firefox uses too much memory or CPU resources - How to fix
• Firefox uses too much memory or CPU resources - How to fix

I have a 50/5 fiber connection and an i7 2.5Ghz with 8Gb ram. Don't think that's an issue. As it has showed up suddenly, more specifically after the update. I know correlation is not always causation, however. So I am open minded.

You can try to create a new profile to test if your current profile is causing the problem.

See "Creating a profile":

• https://support.mozilla.org/kb/profile-manager-create-and-remove-firefox-profiles
• http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Profile_issues

If the new profile works then you can transfer files from a previously used profile to the new profile, but be cautious not to copy corrupted files to avoid carrying over problems.

• http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox

Boot the computer in Windows Safe Mode with network support (press F8 on the boot screen or hold down the Shift key) to see if that has effect.

• http://www.bleepingcomputer.com/tutorials/how-to-start-windows-in-safe-mode/
• http://www.7tutorials.com/4-ways-boot-safe-mode-windows-10