<?php
/**
 * @package      parsetime
 * @author       JeXuS <jexus@jexus.net>
 * @filesource
**/


/**
 * Return normal microtime in float format
 *
 * @return   float
 * @access   public
**/
function get_microtime ()
{
   return array_sum (explode (' ', microtime ()));
}

/**
 * output buffer function, replaces placeholder with real time
 *
 * @param    string    data   returned from ob
 * @return   string
 * @access   private
**/
function _ob_parsetime_replacer ($data)
{
   // the current time
   $time = number_format (get_microtime () - $GLOBALS['parse_time'], 5);
   // the placeholder
   $_placeholder = '{|**PARSE_TIME_PLACE**|}';

   // position of the placeholder
   $pos = strrpos ($data, $_placeholder);

   // replace that substring with the time
   return substr_replace ($data, $time, $pos, strlen ($_placeholder));
}

/**
 * holds first microtime
 *
 * @global   float     $GLOBALS['parse_time']
 * @access   private
**/
$GLOBALS['parse_time'] = get_microtime ();

ob_start ('_ob_parsetime_replacer');
?>

en nu ergens in je html:

{|**PARSE_TIME_PLACE**|}