<?php
//die;
set_time_limit(0);
class Timer
{
    public $timer = 0;

    public function start()
    {
        $mtime = microtime();
        $mtime = explode(" ", $mtime);
        $mtime = $mtime[1] + $mtime[0];
        $this->timer = $mtime;
    }

    public function end()
    {
        $mtime = microtime();
        $mtime = explode(" ", $mtime);
        $mtime = $mtime[1] + $mtime[0];
        $tend = $mtime;
        $totalTime = ($tend - $this->timer);
        $totalTime = sprintf("%2.4f s", $totalTime);
        return $totalTime;
    }
}

$timer = new Timer();

$n = 1000;

$url = 'http://site.com/';

$totalRevo = 0;
$time = array();
for ($i = 0; $i < $n; $i++) {
    $timer->start();
    $revo = file_get_contents($url);
    $revot = $timer->end();
    $time[] = $revot;
    $totalRevo += $revot;
}

$averageRevo = $totalRevo / $n;

echo 'URL источника данных: <a href="' . $url . '">'$url."</a>\n<br />";
echo 'Кол-во повторов: ' . $n . "\n<br />";
echo 'Среднее время загрузки: ' . $averageRevo . "\n<br />";
echo 'Макс время загрузки: ' . max($time) . "\n<br />";
echo 'Мин время загрузки: ' . min($time);
echo '<pre>';
print_r($time);
echo '</pre>';
?>