Fastest way to check for an empty PHP array

empty_arr_bench.php

<?php

$empty = [];
$uniform = [];
$integer = [];
$string = [];
$mixed = [];
$assoc = [];

for ($i = 0; $i < 500000; $i++) {
    $iMd5 = md5((string) $i);

    $uniform[] = 0;
    $integer[] = $i;
    $string[] = $iMd5;
    $mixed[] = $i % 2 ? $i : $iMd5;
    $assoc[$iMd5] = $i;
}

$results = [
    'Empty' => getTimes($empty),
    'Uniform' => getTimes($uniform),
    'Integer' => getTimes($integer),
    'String' => getTimes($string),
    'Mixed' => getTimes($mixed),
    'Associative' => getTimes($assoc),
];

$totals = [];

for ($i = 0; $i < 4; $i++) {
    $total = 0.0;
    foreach ($results as $result) {
        $total += $result[$i];
    }
    $totals[] = $total;
}

echo "             |    count     |    empty     |    === []    |     cast     |\n";
echo "-------------|--------------|--------------|--------------|--------------|\n";

foreach ($results as $name => $times) {
    echo getTitleCol($name) . formatTimes($times);
}

echo "-------------|--------------|--------------|--------------|--------------|\n";
echo getTitleCol('Total') . formatTimes($totals);

/**
 * @return array{float, float, float, float}
 */
function getTimes(array $arr): array
{
    $nt = 90000000;
    $t0 = microtime(true);

    for ($i = 0; $i < $nt; $i++) {
        count($arr) === 0;
    }

    $t1 = microtime(true);
    for ($i = 0; $i < $nt; $i++) {
        empty($arr);
    }

    $t2 = microtime(true);
    for ($i = 0; $i < $nt; $i++) {
        $arr === [];
    }

    $t3 = microtime(true);
    for ($i = 0; $i < $nt; $i++) {
        !$arr;
    }
    $t4 = microtime(true);

    return [$t1 - $t0, $t2 - $t1, $t3 - $t2, $t4 - $t3];
}

function getTitleCol(string $title): string
{
    return str_pad($title, 12, ' ', STR_PAD_LEFT) . ' |';
}

/**
 * @param non-empty-list<float> $times
 */
function formatTimes(array $times): string
{
    $minIndex = array_keys($times, min($times))[0];
    $formatted = [];

    foreach ($times as $i => $time) {
        $str = number_format($time, 6);
        if ($i === $minIndex) {
            $formatted[] = " * $str   "; // if fastest put star before number
        } else {
            $formatted[] = "   $str   ";
        }
    }

    return implode('|', $formatted) . "|\n";
}