use strict;
use warnings;

use Benchmark q{cmpthese};

my $nullFile = q{/dev/null};
open my $nullFH, q{>}, $nullFile
   or die qq{open: $nullFile: $!\n};

my $rcConcat = sub
   {
       print $nullFH q{a} . q{!} x 5 for 1 .. 10000;
   };

my $rcList = sub
   {
       print $nullFH q{a}, q{!} x 5 for 1 .. 10000;
   };

cmpthese (-3,
   {
      Concat     => $rcConcat,
      List       => $rcList,
   });

close $nullFH
   or die qq{close: $nullFile: $!\n};