The ajax_search has a message 'ajaxTimeoutErrorMessage. But it is never defined.

includes\templates\bootstrap\jscript\ajax_search.js line 48
PHP Code:
alert(ajaxTimeoutErrorMessage); 
So if there is a timeout the pages seems to hang and the user does not know there has been a timeout.
If you have the debug consol open, you can see the message "Uncaught ReferenceError: ajaxTimeoutErrorMessage is not defined"