runserver as in "manage.py runserver"? An issue I have hit a few times is when the app is making a request to itself, but runserver cannot serve requests concurrently. Say, browser loads request A and waits for response. While processing request A, the python code makes an internal request B and waits for response. This deadlocks because runserver will not start processing B before A has finished. Eventually request A times out, and if it was just some tracking call, the page appears to load, just after a long pause.