in_array vs array_key_exists vs isset

<?php

$functions = [
    'array_flip & isset' => function (array $haystack, array $needles) {
        $haystackFlip = array_flip($haystack);
        foreach ($needles as $key => $needle) {
            if (!isset($haystackFlip[$needle])) {
                unset($needles[$key]);
            }
        }
        return $needles;
    },
    'array_key_exists (prepared)' => function (array $haystack, array $needles) {
        foreach ($needles as $key => $needle) {
            if (!array_key_exists($needle, $haystack)) {
                unset($needles[$key]);
            }
        }
        return $needles;
    },
//    'array_flip & array_key_exists' => function (array $haystack, array $needles) {
//        $haystackFlip = array_flip($haystack);
//        foreach ($needles as $key => $needle) {
//            if (!array_key_exists($needle, $haystackFlip)) {
//                unset($needles[$key]);
//            }
//        }
//        return $needles;
//    },
    'in_array' => function (array $haystack, array $needles) {
        foreach ($needles as $key => $needle) {
            if (!in_array($needle, $haystack)) {
                unset($needles[$key]);
            }
        }
        return $needles;
    },
//    'in_array & array_unique' => function (array $haystack, array $needles) {
//        $haystack = array_unique($haystack);
//        foreach ($needles as $key => $needle) {
//            if (!in_array($needle, $haystack)) {
//                unset($needles[$key]);
//            }
//        }
//        return $needles;
//    },
];

$needles = [
    'foo',
    'bar',
    'baz',
    'beng',
    'floo',
];

function generateRandomString($length = 10)
{
    $characters = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
    $randomString = '';
    for ($i = 0; $i < $length; $i++) {
        $randomString .= $characters[rand(0, 61)];
    }
    return $randomString;
}

function arrayFactory(int $num, array $mustInclude = []): array
{
    if ($num < count($mustInclude)) {
        $mustIncludeRest = array_splice($mustInclude, 0, $num);
        $mustInclude = $mustIncludeRest;
    }
    if ($num > count($mustInclude)) {
        for ($i = $num - count($mustInclude); $i > 0; $i--) {
            $mustInclude[] = generateRandomString(rand(20, 100));
        }
    }
    shuffle($mustInclude);
    return $mustInclude;
}

$canaries = [];
for ($j = 100000; $j >= 1; $j /= 10) {
    $canaries[$j . ' no match'] = arrayFactory($j);
    $canaries[$j . ' matches'] = arrayFactory($j, $needles);
}
$canaries['0'] = [];

$durations = [];

$results = [];

foreach ($functions as $functionLabel => $function) {
    foreach ($canaries as $canaryLabel => $canary) {
        if ($functionLabel === 'array_key_exists (prepared)') {
            $canary = array_flip($canary);
        }
        $results[$canaryLabel][$functionLabel] = $function($canary, $needles);
        $start = microtime(true);
        for ($k = 0; $k < 1000; $k++) {
            $function($canary, $needles);
        }
        $end = microtime(true);
        $duration = $end - $start;
        $durations[$canaryLabel][$functionLabel] = $duration;
    }
}
foreach ($durations as &$functionDurations) {
    arsort($functionDurations);
}
foreach ($results as $canLabel => $fnRes) {
    $curr = null;
    foreach ($fnRes as $func => $res) {
        if (null === $curr) {
            $curr = $res;
        } elseif ($curr !== $res) {
            throw new Exception('Wer Mist misst, misst Mist');
        }
    }
}

var_export($durations);

Results:

<?php
[
    '100000 no match' => [
        'array_flip & isset' => 8.823206901550293,
        'in_array' => 4.052308082580566,
        'array_key_exists (prepared)' => 0.004848003387451172,
    ],
    '100000 matches' => [
        'array_flip & isset' => 8.786531925201416,
        'in_array' => 1.4839370250701904,
        'array_key_exists (prepared)' => 0.004310131072998047,
    ],
    '10000 no match' => [
        'array_flip & isset' => 0.255079984664917,
        'in_array' => 0.11234402656555176,
        'array_key_exists (prepared)' => 0.004889011383056641,
    ],
    '10000 matches' => [
        'array_flip & isset' => 0.2567770481109619,
        'in_array' => 0.07295012474060059,
        'array_key_exists (prepared)' => 0.004347085952758789,
    ],
    '1000 no match' => [
        'array_flip & isset' => 0.018695831298828125,
        'in_array' => 0.015958070755004883,
        'array_key_exists (prepared)' => 0.004851818084716797,
    ],
    '1000 matches' => [
        'array_flip & isset' => 0.01786518096923828,
        'in_array' => 0.009994029998779297,
        'array_key_exists (prepared)' => 0.004354953765869141,
    ],
    '100 no match' => [
        'in_array' => 0.008791923522949219,
        'array_key_exists (prepared)' => 0.004847049713134766,
        'array_flip & isset' => 0.0047550201416015625,
    ],
    '100 matches' => [
        'in_array' => 0.0062220096588134766,
        'array_key_exists (prepared)' => 0.004394054412841797,
        'array_flip & isset' => 0.004287004470825195,
    ],
    '10 no match' => [
        'in_array' => 0.004911184310913086,
        'array_key_exists (prepared)' => 0.0048677921295166016,
        'array_flip & isset' => 0.003576040267944336,
    ],
    '10 matches' => [
        'in_array' => 0.004410982131958008,
        'array_key_exists (prepared)' => 0.004339933395385742,
        'array_flip & isset' => 0.0031058788299560547,
    ],
    '1 no match' => [
        'in_array' => 0.004850864410400391,
        'array_key_exists (prepared)' => 0.004825115203857422,
        'array_flip & isset' => 0.003459930419921875,
    ],
    '1 matches' => [
        'in_array' => 0.005812883377075195,
        'array_key_exists (prepared)' => 0.004786968231201172,
        'array_flip & isset' => 0.0034101009368896484,
    ],
    0 => [
        'in_array' => 0.007040977478027344,
        'array_key_exists (prepared)' => 0.004853010177612305,
        'array_flip & isset' => 0.0034339427947998047,
    ],
];