That’s weird and frustrating! Well, it usually stems from the servers time “max_input_time.” This is the maximum time in seconds a script is allowed to parse input data, like POST, GET and file uploads. With that said, look through the current script (or functions, etc) and look for a things like…
<?php echo file_get_contents('http://external-url-taking-forever-to-load.com/shmurl.php'); ?>