How to output matches from 2 arrays?

Question

PHP

Good day.
How to quickly and correctly display elements of the first array repeated in another array?
For example:

$array = [
    "1" => "foo",
    "2" => "bar",
];

$array2 = [
    "1" => "def",
    "2" => "foo",
];

$array2 = [
    "1" => "dec",
    "2" => "foo",
];

Should output foo to another array.
I use this method - I compare in a loop all the elements of the array with the next array, and send all matches to another array. But this is a long time, taking into account the fact that there can be many arrays and the number of their elements can reach 10 million.

Answer 1

array_unique(array_intersect($array, $array2))
But as you were told above, it's better to divide such a volume...
and so, when testing for 100k elements in arrays (only numbers), the execution takes about 1MB of memory