I just went through several lockups yesterday. Amazon's homepage in Safari, Chrome and Firefox all locked up my Mac. I had to power off and on each time.
So using NoScript and Firefox , I blocked "images.amazon.com" and that was the workaround. It blocked whatever was causing the problem, yet I could use the website.
Today all went well. "images.amazon.com" was replaced by "images-amazon.com". So indeed Amazon knew their page was locking up browsers.
I reported this here and in Amazon's Support forum. The moderator gave me a link: https://www.amazon.com/gp/help/customer/contact-us/q
that should get us in touch with their engineers.
The Amazon Help Community forums can't address website issues. You'll just wind up with opinions on what's wrong.
Gene