PHP native Quicksort vs Merge Sort

<?php

$n = $argv[1] ?? 1000;

$data = [
    //
];

/**
 * Sort an array by recursively merging a left and right sub array in order.
 * O(N log N) time and O(N) space complexity.
 *
 * @param  array  $data
 * @return array
 */
function msort(array $data = []) : array
{
    $count = count($data);

    if ($count < 2) {
        return $data;
    }

    $left = msort(array_splice($data, 0, ceil($count / 2)));
    $right = msort($data);

    $counter1 = 0;
    $counter2 = 0;
    $sorted = [];

    foreach (range(0, $count - 1) as $i) {
        if ($counter1 === count($left)) {
            $sorted[$i] = $right[$counter2];

            ++$counter2;
        } else if (($counter2 === count($right)) || ($left[$counter1] < $right[$counter2])) {
            $sorted[$i] = $left[$counter1];

            ++$counter1;
        } else {
            $sorted[$i] = $right[$counter2];

            ++$counter2;
        }
    }

    return $sorted;
}

echo 'Sorting ' . number_format($n) . ' random integers between -5000 and 5000' . "\n";

foreach (range(0, $n - 1) as $i) {
    $data[$i] = rand(-5000, 5000);
}

echo 'Testing native PHP quicksort ... ';

$start = microtime(true);

sort($data);

echo 'done in ' . (string) round(microtime(true) - $start, 5) . ' seconds.' . "\n";

foreach (range(0, $n - 1) as $i) {
    $data[$i] = rand(-5000, 5000);
}

echo 'Testing merge sort ... ';

$start = microtime(true);

$sorted = msort($data);

echo 'done in ' . (string) round(microtime(true) - $start, 5) . ' seconds.' . "\n";

readline('Press any key to dump results ... ');

var_dump($sorted);

Results:

Sorting 1,000 random integers between -5000 and 5000
Testing native PHP quicksort ... done in 0.00019 seconds.
Testing merge sort ... done in 0.00246 seconds.