It is possible that there is a conflict somewhere between the site's plugins and your browser's add on if not your computer resources. You should try to install another browser (chrome if possible) and check if it fixes the issue.
Anyway, have you installed Microsoft Edge? Does it fix the problem?
You are right. I did install a fresh Microsoft Edge browser and it loaded without any problems. I also uninstalled all the add-ons I had on FireFox, and I was able to access the site with no challenge. I think one of the add-ons was causing the issue though I am yet to figure out which on it was.