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();  
?>