This also can be a client-side or networking issue. If you do not close the 'hang' browser window and keep waiting, will it return the page content finally? If so, open the site's property in IIS manager and configure logging, enable the 'time-taken' field. Try reproducing the problem again and then verify IIS log to see how long time is recorded.
Furthermore, using tools like fiddler to monitor and capture networking traces may give us a more clear view of the issue.