array_change_key_case_bench.php

<?php
// array_change_key_case.php
$cnt = 1000;
$ret = array();
$array = makeAssoc($cnt);

while ($cnt--) {
    $ret = array_change_key_case($array);
}

// foreach.php
$cnt = 1000;
$ret = array();
$array = makeAssoc($cnt);

while ($cnt--) {
    foreach ($array as $k => $v) {
        $k = strtolower($k);
        $ret[$k] = $v;
    }
}

// common func
function makeAssoc($cnt) {
    $ret = array();
    $i = $cnt;
    while ($i--) {
        $key = getRandomString();
        $ret[$key] = $key;
    }

    return $ret;
}   

// http://www.ecoop.net/memo/2005-05-31-1.html
function getRandomString($len = 8) {
    $char_list = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_';
    mt_srand(); 
    $res = '';
    for ($i = 0; $i < $len; $i++) {
        $res .= $char_list {
            mt_rand(0, strlen($char_list) - 1)
        };
    }
    return $res;
}