这有一个测试页面执行时间的类：

<?
class timer {  
    var $StartTime = 0;  
    var $StopTime = 0;  
    var $TimeSpent = 0;  

    function start(){  
        $this->StartTime = microtime();  
    }  

    function stop(){  
        $this->StopTime  = microtime();  
    }  

    function spent() {  
        if ($this->TimeSpent) {  
            return $this->TimeSpent;  
        } else {  
            $StartMicro = substr($this->StartTime,0,10);  
            $StartSecond = substr($this->StartTime,11,10);  
            $StopMicro  = substr($this->StopTime,0,10);  
            $StopSecond  = substr($this->StopTime,11,10);  
            $start = doubleval($StartMicro) + $StartSecond;  
            $stop  = doubleval($StopMicro) + $StopSecond;  
            $this->TimeSpent = $stop - $start;  
            return substr($this->TimeSpent,0,8)."秒";  
        }  
    }  // end function spent();  

} //end class timer;  

//例子：  
    $timer = new timer;  
    $timer->start();  
/*
你的代码放在此处
*/

    $timer->stop();  
    echo "执行本SCRIPT共".$timer->spent();  
?>

原文转自：http://www.ltesting.net