#!/user/bin/perl
use strict;
use warnings;
use Benchmark qw[ cmpthese ];

sub sum_copy {
    my @numbers = @_;
    my $sum = 0;
    foreach my $num (@numbers){ $sum += $num }
    $sum;
}

sub sum_ref {
    my ($numbers_ref) = @_;
    my $sum = 0;
    foreach my $num (@$numbers_ref){ $sum += $num };
    $sum;
}

our $N //= 1e6;

my @numbers = 1 .. $N;

cmpthese -3, {
    copy => sub{ my $sum = sum_copy( @numbers ); },
    ref  => sub{ my $sum = sum_ref( \@numbers ); },
};

__END__
C:\test>junk28 -N=1e4
       Rate copy  ref
copy 3.92/s   -- -59%
ref  9.67/s 146%   --

C:\test>junk28 -N=1e5
       Rate copy  ref
copy 3.95/s   -- -59%
ref  9.62/s 144%   --

C:\test>junk28 -N=1e6
       Rate copy  ref
copy 3.92/s   -- -59%
ref  9.66/s 146%   --