(naieve fibonacci) like this:

    <?php
    
    function fib($n) 
    {
        if($n === 0) { return 1;}
        if($n === 1) { return 1;}
        $r = fib($n-1) + fib($n-2);
        return $r;
    }
    

    $n= (int) $argv[1];
    $r = fib($n);
    printf("%d %d\n",$n,$r);

just did some measurements on my laptop:

    | Language             |  n | time(s) |
    |----------------------+----+---------|
    | php (7.4.25)         | 42 |   422.0 |
    | python3              | 42 |    90.0 |
    | haskell (ghc -O3)    | 42 |    13.8 |
    | f#                   | 42 |     5.6 |
    | ts                   | 42 |     2.8 |
    | ocaml (ocamlopt -O3) | 42 |    0.98 |
    | C (gcc -O3)          | 42 |    0.66 |

(edit: added php version in table. )