php mysql multiple insert

mysql.php

<?php

try {
	$dbh = new PDO('mysql:host=localhost;dbname=mytest', 'root', '123', array(
		PDO::ATTR_PERSISTENT => true));

	$rows = array(
		array(null, 'def', time()),
		array(null, 'def', time()),
		array(null, 'def', time()),
		array(null, 'def', time()),
		array(null, 'def', time()),
	);
	for ($i = 0; $i < 10000; $i++) {
		array_push($rows, array(null, 'def', time()));
	}

	$t1 = microtime(true);

	$args = array_fill(0, count($rows) * count($rows[0]), '?');

	$params = array();
	$query = "INSERT INTO ntable (id, name, ntime) VALUES ";
	foreach ($rows as $row) {
		$query .= "(?,?,?),";
		foreach ($row as $value) {
			$params[] = $value;
		}
	}
	$query = substr($query, 0, -1);

	$stmt = $dbh->prepare($query);
	if (!$stmt) {
		echo "\nPDO::errorInfo():\n";
		print_r($dbh->errorInfo());
	}
	$r = $stmt->execute($params);

	$t2 = microtime(true);
	echo (($t2 - $t1) * 1000) . 'ms';

} catch (PDOException $e) {
	print "Error!: " . $e->getMessage() . "<br/>";
	die();
}

//result 380.75590133667ms