Record page execution time php code

class runtime
{
 var $StartTime = 0;
 var $StopTime = 0;

 function get_microtime()
 {
 list($usec, $sec) = explode(' ', microtime());
 return ((float)$usec + (float)$sec);
 }

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

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

 function spent()
 {
 return round(($this->StopTime - $this- >StartTime) * 1000, 1);
 }

}

//Example
$runtime= new runtime;
$runtime->start();

//Your code starts

$a = 0;
for($i=0; $i<1000000; $i++)
{
 $a += $i;
}

//End of your code

$runtime->stop();
 echo "Page execution time: ".$runtime->spent()." milliseconds";
?>

Execution time, php