I was asked to troubleshoot why a site wasn't loaded or responding properly, it turned out they were using some old javascript tracker from Bing/Microsoft that is no longer valid or working. You have to wait forever for it to time out but it really did disrupt the functionality of a very important site:
flex.atdmt.com
If you have the above code in javascript on your site remove or comment it out.
bing, microsoft, ads, flex, atdmt, loadingi, troubleshoot, wasn, responding, javascript, tracker, valid, disrupt, functionality,