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;