I was recently debugging Web Site functionality issue with a client. We were not able to reproduce the issues at our end. I saw that the client has disable F12 developer Tool on user computer. I requested them to enable the F12 developer tool. They did and send amazing information. IE11 was hanging on one missing web trend file and was taking 10 - 15 minutes before hanging. Chrome was working fine. Chrome was taking only 2-3 seconds.
F12 Developer Tool vs Fiddler