PHP PDO slow fetch with a lot of bind parameters benchmark

bench_pdo.php

<?php

declare(strict_types=1);

function genData(int $cnt): array {
	$data = [];

	for($i = 0; $i < $cnt; ++$i) {
		$data[] = [
			'str1' => uniqid(),
			'str2' => uniqid(),
			'num' => rand(),
		];
	}

	return $data;
}

$data = genData(8000);

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

$vals = [];
foreach($data as $row) {
	$vals[] = $row['str1'];
	$vals[] = $row['str2'];
	$vals[] = $row['num'];
}
$valSql = \implode(', ', \array_fill(0, \count($data), '(?, ?, ?)'));
$sql = <<<SQL
	INSERT INTO thingies (str1, str2, num)
	VALUES {$valSql}
	RETURNING id, str2
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
);