This is one of the possible ways:
Please look at the onSubmit attribute of form: http://www.htmlcodetutorial.com/forms/_FORM_onSubmit.html
attribute points to the same URL of the current page (always a good idea). So, when the page is rendered, the user will see the content without this indicator. Based on this idea, you can implement different effect except… showing the percentage of loaded content; but there is not a reason to be sorry about it: this time is pretty much unpredictable anyway.