Description:
------------
I discovered `COUNT_RECURSIVE` and thought it would speed up my algorithm. But instead, it slowed it down. It initially used `array_sum` + `array_map`. See the test script.

This result is surprising because `array_map` creates a new array, so the memory allocations should be slower than just iterating and counting. It proofs to be true with the last test in the script (see “manual”) where it is faster than all the previous solutions.

Test script:
---------------
<?php

const LENGTH = 100000;

$a = array_fill(0, LENGTH, array_fill(0, LENGTH, 42));

echo 'expected:            '; var_dump(LENGTH * LENGTH);
echo "\n\n";

$_ = microtime(true);
echo 'count recursive:     '; var_dump(count($a, COUNT_RECURSIVE) - count($a));
echo 'time: ', number_format((microtime(true) - $_) / 1000, 6), "\n\n";

$_ = microtime(true);
echo 'sum + map:           '; var_dump(array_sum(array_map('count', $a)));
echo 'time: ', number_format((microtime(true) - $_) / 1000, 6), "\n\n";

$_ = microtime(true);
echo 'sum + map + closure: '; var_dump(array_sum(array_map(function (array $v) { return count($v); }, $a)));
echo 'time: ', number_format((microtime(true) - $_) / 1000, 6), "\n\n";

$_ = microtime(true);
echo 'manual:              ';
$i = 0;
foreach ($a as $aa) {
    $i += count($aa);
}
var_dump($i);
echo 'time: ', number_format((microtime(true) - $_) / 1000, 6), "\n\n";


/**
 * Output:
 *
 *     expected:            int(10000000000)
 *
 *
 *     count recursive:     int(10000000000)
 *     time: 0.012170
 *
 *     sum + map:           int(10000000000)
 *     time: 0.000005
 *
 *     sum + map + closure: int(10000000000)
 *     time: 0.000007
 *
 *     manual:              int(10000000000)
 *     time: 0.000002
 */


Expected result:
----------------
`COUNT_RECURSIVE` should be as fast as or faster than `array_sum` + `array_map`.

`COUNT_RECURSIVE` should be as fast as the “manual” test, or even faster because it's written in C directly.

Actual result:
--------------
`COUNT_RECURSIVE` is way too slow :-).