Something

<?php
if(isset($_GET['test1'])) {
	$start = explode(" ", microtime()); $start = $start[0] + $start[1]; for ($idx = 0; $idx < 1000000; $idx++) {
		$result[$index+$idx] = $idx;
	}
	$end = explode(" ", microtime()); $end = $end[0] + $end[1];

	echo "Time: ".($end - $start);
}
if(isset($_GET['test2'])) {
	$start = explode(" ", microtime()); $start = $start[0] + $start[1]; for ($idx = 0; $idx < 1000000; $idx++) {
		if(!isset($index))
		$index = '';
		if(!isset($result))
		$result = array();
		$result[$index+$idx] = $idx;

		unset($result);
		unset($index);
	}
	$end = explode(" ", microtime()); $end = $end[0] + $end[1];

	echo "Time: ".($end - $start);

}
?>