Reported by email:
The browser continues to request the returned page and appends the text after the hashtag to the end of the url. When the page is loaded again, the arbitrary text is executed again and the loop will continue indefinitely. It only takes a couple of browsers to do this to notice the increased load on the webserver.
URL to reproduce: index.php?module=CoreHome&action=index&idSite=1&period=range&date=previous30#blabla
(In ) Fixes #3471, make sure broadcast won't show AJAX result if result is whole HTML document.