Yes, and lol, I was the guy who posted as much in that other thread. I posted this thread before I found that one where I got the idea to check my add-ons.
I found the extension that was causing this for me: NordVPN - a VPN proxy extension for Firefox.I disabled this, reopened Firefox, and it was back to normal. But once I re-enabled the extension, all the other tabs started refreshing immediately.I'll...