array_replace() vs array union benchmark

array_add.php

<?php

for ($i = 0; $i < 1000000; ++$i) {
    $server = $_SERVER;
    $server += array(
        'SERVER_NAME'          => 'localhost',
        'SERVER_PORT'          => 80,
        'HTTP_HOST'            => 'localhost',
        'HTTP_USER_AGENT'      => 'Symfony/2.X',
        'HTTP_ACCEPT'          => 'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8',
        'HTTP_ACCEPT_LANGUAGE' => 'en-us,en;q=0.5',
        'HTTP_ACCEPT_CHARSET'  => 'ISO-8859-1,utf-8;q=0.7,*;q=0.7',
        'REMOTE_ADDR'          => '127.0.0.1',
        'SCRIPT_NAME'          => '',
        'SCRIPT_FILENAME'      => '',
        'SERVER_PROTOCOL'      => 'HTTP/1.1',
        'REQUEST_TIME'         => time(),
    );
}

array_replace.php

<?php

for ($i = 0; $i < 1000000; ++$i) {
    $server = $_SERVER;
    $server = array_replace(array(
        'SERVER_NAME'          => 'localhost',
        'SERVER_PORT'          => 80,
        'HTTP_HOST'            => 'localhost',
        'HTTP_USER_AGENT'      => 'Symfony/2.X',
        'HTTP_ACCEPT'          => 'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8',
        'HTTP_ACCEPT_LANGUAGE' => 'en-us,en;q=0.5',
        'HTTP_ACCEPT_CHARSET'  => 'ISO-8859-1,utf-8;q=0.7,*;q=0.7',
        'REMOTE_ADDR'          => '127.0.0.1',
        'SCRIPT_NAME'          => '',
        'SCRIPT_FILENAME'      => '',
        'SERVER_PROTOCOL'      => 'HTTP/1.1',
        'REQUEST_TIME'         => time(),
    ), $server);
}

results

php -v
PHP 5.4.6-1ubuntu1.1 (cli) (built: Nov 15 2012 01:18:34) 
Copyright (c) 1997-2012 The PHP Group
Zend Engine v2.4.0, Copyright (c) 1998-2012 Zend Technologies

time php array_replace.php

real    0m4.961s
user    0m4.948s
sys     0m0.000s

real    0m4.905s
user    0m4.888s
sys     0m0.004s

real    0m4.878s
user    0m4.856s
sys     0m0.008s


time php array_add.php

real    0m2.967s
user    0m2.948s
sys     0m0.008s

real    0m2.980s
user    0m2.972s
sys     0m0.004s

real    0m2.993s
user    0m2.980s
sys     0m0.004s