use Benchmark 'cmpthese';

my @data = map { rand } 0 .. 4000;

cmpthese(-2, {
  copy => sub { copy(@data) },
  ref  => sub { ref(\@data) }
});

sub copy { my $sum; $sum += $_[$_]    for 0 .. $#_;       return $sum }
sub ref  { my $sum; $sum += $_[0][$_] for 0 .. $#{$_[0]}; return $sum }

__END__
          Rate    copy     ref
copy     370/s      --   -100%
ref  1884708/s 508700%      --