gistfile1.php

<?php
echo "500000 loops of \$foo = array('i' => \$i);\n";
$start = microtime(true);

for ($i=0; $i < 500000; $i++) {
                  $foo = array(
                                         'i' => $i
                  );
}

$end = microtime(true);
$timeTook = $end - $start;
echo "LongTook: {$timeTook}\n";

$start = microtime(true);

for ($i=0; $i < 500000; $i++) {
                  $foo = [
                                         'i' => $i
                  ];
}

$end = microtime(true);
$timeTook = $end - $start;
echo "ShortTook: {$timeTook}\n";