Since updating to FF43, under Windows Vista, I get a "Not Responding" message anytime I visit a web page on Amazon.com that contains product information for a Kindle book. For example, http://www.amazon.com/gp/product/B0189WSN9K/. I even tried starting up FireFox in safe mode and got the same result. I also tried it after logging out of Amazon first. When I pull up the task manager, it shows FireFox using about 25% of available CPU, and the amount of memory used just constantly increases. I let it run for about an hour before terminating it, and it went from about 350KB to 3MB of memory. I suspect it's in some kind of loop...? If I hit ESC at the right time, to stop the page loading, I can get a web page displayed that appears complete and fully functional. But if I'm too late, I need to terminate FireFox and restart it. Too early, and I need to try and load the web page again. Usually, it takes about 5 to 10 seconds to get the "Not Responding" result. Others with FF43 have told me they don't have a problem with the example web page I gave above. And it works fine for me in Chrome. Any ideas or suggestions?