sub sum1{ 
    my @numbers = @_; 
    my $total = 0; 
    for my $number ( @numbers ){ 
        $total = "$total" + "$number" 
    } 
    return $total 
};;

sub sum2{ 
    my $total = 0; 
    $total += $_ for @{ $_[0] }; 
    return $total 
};;

@n = 1 .. 1e6;;

cmpthese -1, { A=>q[ my $total=sum1( @n ); ], B=>q[ my $total=sum2( \@n ); ] };;

    Rate    A    B
A 1.03/s   -- -90%
B 10.8/s 949%   --