Simple benchmark of PHP build-in functions for arrays and general foreach.

php-arrays.php

<?php

ini_set('memory_limit', '4G');

$last_time = microtime(TRUE);
function timer() {
	global $last_time;
	$previous = $last_time;
	$last_time = microtime(TRUE);
	return $last_time - $previous;
}

function generate_array($size) {
	$array = array();
	for ($i = 0; $i < $size; $i++) {
		$array[] = $i;
	}
	return $array;
}

function test_array_filter($array) {
	$filter = function ($i) {
		return $i % 2 == 0;
	};

	timer();
	$filtered = array_filter($array, $filter);
	echo timer() . "\n";

	timer();
	$filtered = array();
	foreach ($array as $i) {
		if ($filter($i)) {
			$filtered[] = $i;
		}
	}
	echo timer() . "\n";

	timer();
	$filtered = array();
	foreach ($array as $i) {
		if ($i % 2 == 0) {
			$filtered[] = $i;
		}
	}
	echo timer() . "\n";
}

function test_array_reduce($array) {
	$reduce = function ($sum, $i) {
		return $sum + $i;
	};

	timer();
	$sum = array_reduce($array, $reduce, 0);
	echo timer() . "\n";

	timer();
	$sum = 0;
	foreach ($array as $i) {
		$sum = $reduce($sum, $i);
	}
	echo timer() . "\n";

	timer();
	$sum = 0;
	foreach ($array as $i) {
		$sum = $sum + $i;
	}
	echo timer() . "\n";

	timer();
	$sum = array_sum($array);
	echo timer() . "\n";
}

function test_array_map($array) {
	$mapper = function ($num) {
		return $num + 1;
	};

	timer();
	array_walk($array, $mapper);
	echo timer() . "\n";

	timer();
	foreach ($array as $key => $i) {
		$array[$key] = $mapper($i);
	}
	echo timer() . "\n";

	timer();
	foreach ($array as $key => $i) {
		$array[$key] = $i + 1;
	}
	echo timer() . "\n";
}

function test_array_walk($array) {
	timer();
	array_walk($array, function () {});
	echo timer() . "\n";

	timer();
	foreach ($array as $i) {}
	echo timer() . "\n";
}

// $array_sizes = array(10, 50, 100, 200, 500, 1000);
$array_sizes = array(1000, 5000, 10000, 50000, 100000, 500000, 1000000);

foreach ($array_sizes as $size) {
	echo $size . "\n";

	$array = generate_array($size);

	echo "array_filter\n";
	test_array_filter($array);

	echo "array_reduce\n";
	test_array_reduce($array);

	echo "array_map\n";
	test_array_map($array);

	echo "array_walk\n";
	test_array_walk($array);

	echo "\n";
}