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;