gistfile1.php

<?php

define('USE_LINK', true);

$start_time = microtime(true);

$array = array();
for($i =0; $i < 100000; $i++) {
    $array[] = array(
        'mem' => memory_get_usage(),
    );
}

$gen_time = microtime(true);

if(USE_LINK) {
    foreach($array as $k => &$item) {
        $item['time'] = microtime(true);
    }
    unset($item);
} else {
    foreach($array as $k => $item) {
        $array[$k]['time'] = microtime(true);
    }
}

$computed_time = microtime(true);
$mem1 = memory_get_peak_usage();

echo 'mems '.round($mem1/1024/1024, 2)."Mb\r\n";
echo "Gen time: ".($gen_time-$start_time)."\r\n";
echo "Computed time: ".($computed_time-$gen_time)."\r\n";