Closure vs call_user_func performance

test.php

<?php

$iterations = 100000;
$start = microtime(true);
$closure = null;

for ($i = 0; $i < $iterations; $i += 1) {
    if ($closure) {
	    $closure();
	}
}

var_dump(microtime(true) - $start);

$start = microtime(true);
$closure = function () {};

for ($i = 0; $i < $iterations; $i += 1) {
	$closure();
}

var_dump(microtime(true) - $start);

$start = microtime(true);
$closure = function () {};

for ($i = 0; $i < $iterations; $i += 1) {
	call_user_func($closure);
}

var_dump(microtime(true) - $start);