use strict; 
use warnings; 
use Benchmark qw(:all); 

my @a = ( 'a','b','c','d','e','g','h', 'a','b','c','d','e','g','h', 'a','b','c','d','e','g','h', 'a','b','c','d','e','g','h', 'a','b','c','d','e','g','h', 'a','b','c','d','e','g','h', 'a','b','c','d','e','g','h', 'a','b','c','d','e','g','h', 'a','b','c','d','e','g','h', 'a','b','c','d','e','g','h', ); 

my $a_ref = [ 'a','b','c','d','e','g','h', 'a','b','c','d','e','g','h', 'a','b','c','d','e','g','h', 'a','b','c','d','e','g','h', 'a','b','c','d','e','g','h', 'a','b','c','d','e','g','h', 'a','b','c','d','e','g','h', 'a','b','c','d','e','g','h', 'a','b','c','d','e','g','h', 'a','b','c','d','e','g','h', ]; 

cmpthese(-2, { 
  'a copy'  => sub { my @b = a_copy(@a); }, 
  'a ref 1' => sub { my $b = a_ref_1(\@a); }, 
  'a ref 2' => sub { my $b = a_ref_2(\@a); }, 
  'a ref 3' => sub { my $b = a_ref_1($a_ref); }, 
  'a ref 4' => sub { my $b = a_ref_2($a_ref); }, 
}); 

sub a_copy { my (@a) = @_; return @a; } 
sub a_ref_1 { my ($a) = @_; return $a; } 
sub a_ref_2 { return $_[0]; } 

##</code><code>##

 
             Rate a copy a ref 1 a ref 3 a ref 2 a ref 4 
a copy   171189/s    --    -97%    -97%    -97%    -98% 
a ref 1 5073751/s  2864%     --    -15%    -21%    -35% 
a ref 3 5946679/s  3374%    17%     --      -7%    -23% 
a ref 2 6408282/s  3643%    26%      8%     --     -17% 
a ref 4 7753141/s  4429%    53%     30%     21%     --