Websites show a spinning wheel and never finish loading
I ran all the Firefox malware suggesed programs "Websites show a spinning wheel and never finish loading" but none worked. I got an eMail virus that Avast did not catch. I ran their full scan (I normally run the quick) and noticed they also have an option at the bottom for a Boot-Time Scan. I clicked to run it at re-boot and it came up with 2 PUB malwares. I removed them and the Tab wheels have stopped spinning! As for the eMail virus, Avast full scan found nothing but the Microsoft Safety Scanner (recommended by FF) did.
Opaite Mbohovái (1)
It is possible that your security software (firewall, anti-virus) blocks or restricts Firefox or the plugin-container process without informing you, #p#ly 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:
Boot the computer in Windows Safe mode with network support (press F8 on the boot screen) as a test to see if that helps.