PHP lambda performance results

Live version: https://3v4l.org/6AABv

Test script:
<?php

$a = array(
	0 => "foo",
	1 => "bar",
	"animal" => "string",
	3.13 => "pi",
);

$loops = 1000000;

printf("Control loop...\n");
$start = microtime(true);
function process_array($a)
{
	$s = "";
	foreach ($a as $key=>$value)
	{
		$s .= "$key=>$value\n";
	}
}
for ($i = 0; $i < $loops; $i++)
	process_array($a);
$elapsed = microtime(true) - $start;
printf("Elapsed: %.2f s\n\n", $elapsed);

printf("Anonymous lambda function created once and called via reference...\n");
$start = microtime(true);
$process_array_lambda = function($a)
{
	$s = "";
	foreach ($a as $key=>$value)
	{
		$s .= "$key=>$value\n";
	}
};
for ($i = 0; $i < $loops; $i++)
	$process_array_lambda($a);
$elapsed = microtime(true) - $start;
printf("Elapsed: %.2f s\n\n", $elapsed);

printf("Anonymous lambda function called directly...\n");
$start = microtime(true);
for ($i = 0; $i < $loops; $i++)
	(function($a)
	{
		$s = "";
		foreach ($a as $key=>$value)
		{
			$s .= "$key=>$value\n";
		}
	})($a);
$elapsed = microtime(true) - $start;
printf("Elapsed: %.2f s\n\n", $elapsed);
?>

Results:




PHP version 8.0.0:

Control loop...
Elapsed: 0.52 s

Anonymous lambda function created once and called via reference...
Elapsed: 0.53 s

Anonymous lambda function called directly...
Elapsed: 0.71 s


PHP version 7.4.13:

Control loop...
Elapsed: 0.58 s

Anonymous lambda function created once and called via reference...
Elapsed: 0.63 s

Anonymous lambda function called directly...
Elapsed: 0.70 s


PHP version 7.4.12:

Control loop...
Elapsed: 0.57 s

Anonymous lambda function created once and called via reference...
Elapsed: 0.58 s

Anonymous lambda function called directly...
Elapsed: 0.62 s


PHP version 7.4.11:

Control loop...
Elapsed: 0.56 s

Anonymous lambda function created once and called via reference...
Elapsed: 0.52 s

Anonymous lambda function called directly...
Elapsed: 0.65 s


PHP version 7.4.10:

Control loop...
Elapsed: 0.64 s

Anonymous lambda function created once and called via reference...
Elapsed: 0.54 s

Anonymous lambda function called directly...
Elapsed: 0.65 s


PHP version 7.4.9:

Control loop...
Elapsed: 0.53 s

Anonymous lambda function created once and called via reference...
Elapsed: 0.50 s

Anonymous lambda function called directly...
Elapsed: 0.63 s


PHP version 7.4.8:

Control loop...
Elapsed: 0.51 s

Anonymous lambda function created once and called via reference...
Elapsed: 0.53 s

Anonymous lambda function called directly...
Elapsed: 0.70 s


PHP version 7.4.7:

Control loop...
Elapsed: 0.76 s

Anonymous lambda function created once and called via reference...
Elapsed: 0.59 s

Anonymous lambda function called directly...
Elapsed: 0.66 s


PHP version 7.4.6:

Control loop...
Elapsed: 0.52 s

Anonymous lambda function created once and called via reference...
Elapsed: 0.54 s

Anonymous lambda function called directly...
Elapsed: 0.67 s


PHP version 7.3.25:

Control loop...
Elapsed: 0.70 s

Anonymous lambda function created once and called via reference...
Elapsed: 0.61 s

Anonymous lambda function called directly...
Elapsed: 0.70 s


PHP version 7.3.24:

Control loop...
Elapsed: 0.52 s

Anonymous lambda function created once and called via reference...
Elapsed: 0.58 s

Anonymous lambda function called directly...
Elapsed: 0.66 s


PHP version 7.3.23:

Control loop...
Elapsed: 0.72 s

Anonymous lambda function created once and called via reference...
Elapsed: 0.83 s

Anonymous lambda function called directly...

Process exited with code 137.

PHP version 7.3.22:

Control loop...
Elapsed: 0.49 s

Anonymous lambda function created once and called via reference...
Elapsed: 0.60 s

Anonymous lambda function called directly...
Elapsed: 0.68 s


PHP version 7.3.21:

Control loop...
Elapsed: 0.47 s

Anonymous lambda function created once and called via reference...
Elapsed: 0.56 s

Anonymous lambda function called directly...
Elapsed: 0.74 s


PHP version 7.3.20:

Control loop...
Elapsed: 0.54 s

Anonymous lambda function created once and called via reference...
Elapsed: 0.53 s

Anonymous lambda function called directly...
Elapsed: 0.66 s


PHP version 7.3.19:

Control loop...
Elapsed: 0.64 s

Anonymous lambda function created once and called via reference...
Elapsed: 0.86 s

Anonymous lambda function called directly...

Process exited with code 137.

PHP version 7.3.18:

Control loop...
Elapsed: 0.55 s

Anonymous lambda function created once and called via reference...
Elapsed: 0.55 s

Anonymous lambda function called directly...
Elapsed: 0.77 s


PHP version 7.2.34:

Control loop...
Elapsed: 0.87 s

Anonymous lambda function created once and called via reference...
Elapsed: 0.79 s

Anonymous lambda function called directly...

Process exited with code 137.

PHP version 7.2.33:

Control loop...
Elapsed: 0.57 s

Anonymous lambda function created once and called via reference...
Elapsed: 0.62 s

Anonymous lambda function called directly...
Elapsed: 0.73 s


PHP version 7.2.32:

Control loop...
Elapsed: 0.57 s

Anonymous lambda function created once and called via reference...
Elapsed: 0.59 s

Anonymous lambda function called directly...
Elapsed: 0.72 s