Which is faster between comma and dot when in echo statement?

g.php

<?php

const CC = 1e7;

function gg() {
    static $a = 0;
    while ($a < CC) {
        yield $a++;
    }
}

function gg1() {
    static $a = 0;
    while ($a < CC) {
        yield $a++;
    }
}

$s = time();
foreach (gg() as $i) {
    echo $i, $i, PHP_EOL;
}
$e = time();

$s1 = time();
foreach (gg1() as $i) {
    echo $i . $i . PHP_EOL;
}
$e1 = time();

echo ($e - $s), PHP_EOL;
echo ($e1 - $s1), PHP_EOL;