Whew, this was painful one. Recently, we noticed outlook 2016 was taking way too long to create a new user profile. I found this article from The Education University of Hong Kong with a fix. Click here for the link to the article. Basically, you need to modify the registry to bypass the root domain discovery auto-discover process. (WOW: it's like we've traveled back in time to NT4...)
Windows Registry Editor Version 5.00
[HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\16.0\Outlook\AutoDiscover]
"ExcludeHttpsRootDomain"=dword:00000001
Update 8/9/18: https://support.microsoft.com/en-us/help/3098011/outlook-2016-and-outlook-2013-hang-when-a-user-tries-to-create-a-profi
