PHP PDO slow fetch with a lot of bind parameters benchmark (SELECT IN)

bench_pdo.php

<?php

declare(strict_types=1);

$db = new PDO('pgsql:host=localhost;dbname=test', 'test', 'test');
$db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

$N = 65535;

$vals = range(1, $N);

$valSql = \implode(', ', \array_fill(0, \count($vals), '?'));
$sql = <<<SQL
        SELECT * FROM thingies WHERE id IN ({$valSql})
SQL;

$prepStart = \microtime(true);
$query = $db->prepare($sql);
$execStart = \microtime(true);
$query->execute($vals);
$fetchStart = \microtime(true);
$ret = $query->fetchAll();
echo 'Got rows: '.\count($ret).PHP_EOL;
$end = \microtime(true);

$prepDuration = \number_format($execStart - $prepStart, 3);
$execDuration = \number_format($fetchStart - $execStart, 3);
$fetchDuration = \number_format($end - $fetchStart, 3);

//var_dump($ret);

echo "[Timings] prep: {$prepDuration}, exec: {$execDuration}, fetch: {$fetchDuration}".PHP_EOL;

postgres_test_schema.sql

CREATE TABLE thingies (
	id SERIAL PRIMARY KEY,
	str1 TEXT NOT NULL,
	str2 TEXT NOT NULL,
	num INTEGER NOT NULL
);