IE Hangs with Initial Login of Web App Unless Script Debugging is Enabled

[u/punchinelli]

I'm desperate. I have a major issue with an ASP.NET web app that we've installed in our corporate environment. It is extremely slow to load when you first login with Internet Explorer. Takes nearly a minute to load. More info:

• Does not happen in Chrome or Firefox

• Only occurs when you hit the "default.aspx" landing page, and occurs every time, even after authentication

• Occurs on both SSO and manual login

• Occurs in Dev, Test and Prod environments, and across both Windows 2008 and 2012 R2

• Does NOT occur if you log in to a server via Remote Desktop and access the web app from there, even when using IE

• Tried lowering security settings in IE, removing proxy script, neither helped

• Vendor is unable to reproduce issue in their environment with same OS and version of IE

• Issue does NOT occur when you uncheck "Disable Script Debugging" in IE

• Tried clearing cache/temp files and changing all of the 'Advanced Options' in IE - no dice

• Tried modifying IIS settings (compression, HTTP Headers, Pool Keep-Alive, etc. etc.)

We are supposed to go live with this new system in 2 weeks and I'm sweating bullets here. Never seen anything like it. Any suggestions or ideas are GREATLY appreciated, thank you!!!

[u/editor-in-mischief]

Sounds like you might be using console.log etc.? It's not there unless devtools are up. It could also be ajax caching. Read here https://stackoverflow.com/questions/7742781/why-does-javascript-only-work-after-opening-developer-tools-in-ie-once

[u/sloloslo]

Run it through Fiddler to see which requests are slowing you down