'table' => 'use strict; my $a = rot13($data),"\n"',
  'tr'    => 'use strict; my $a = rot13tr($data),"\n"',

##</code><code>##

Benchmark: running table, tr, each for at least 3 CPU seconds...
     table:  4 wallclock secs ( 3.13 usr +  0.00 sys =  3.13 CPU) @ 331.84/s (n=1040)
        tr:  3 wallclock secs ( 3.23 usr +  0.00 sys =  3.23 CPU) @ 65432.56/s (n=211020)
         Rate  table     tr
table   332/s     --   -99%
tr    65433/s 19618%     --

##</code><code>##

#!/usr/bin/perl
use strict;
use warnings;

use Benchmark qw( cmpthese );

my %rot = (
  'A' => 'N','B' => 'O','C' => 'P','D' => 'Q','E' => 'R','F' => 'S',
  'G' => 'T','H' => 'U','I' => 'V','J' => 'W','K' => 'X','L' => 'Y',
  'M' => 'Z','N' => 'A','O' => 'B','P' => 'C','Q' => 'D','R' => 'E',
  'S' => 'F','T' => 'G','U' => 'H','V' => 'I','W' => 'J','X' => 'K',
  'Y' => 'L','Z' => 'M','a' => 'n','b' => 'o','c' => 'p','d' => 'q',
  'e' => 'r','f' => 's','g' => 't','h' => 'u','i' => 'v','j' => 'w',
  'k' => 'x','l' => 'y','m' => 'z','n' => 'a','o' => 'b','p' => 'c',
  'q' => 'd','r' => 'e','s' => 'f','t' => 'g','u' => 'h','v' => 'i',
  'w' => 'j','x' => 'k','y' => 'l','z' => 'm',
);

sub rot13 ($) {
  # as close as possible to source project's code
  join '', map { exists $rot{$_} ? $rot{$_} : $_ } split('',shift);
}

sub rot13tr ($) {
  (my $s = shift) =~ tr/a-zA-Z/n-za-mN-ZA-M/;
  $s;
}

our $data;
{
   local $/;
   $data = <DATA>;
}

cmpthese(-3, {
 #table => 'use strict; use warnings; my $rv = rot13  (our $data); 1',
 #tr    => 'use strict; use warnings; my $rv = rot13tr(our $data); 1',

  table => 'my $rv = rot13  ($data); 1',
  tr    => 'my $rv = rot13tr($data); 1',
});

__DATA__
Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Vivamus
luctus nulla sed tellus. Sed vitae sapien in elit vestibulum faucibus.
Maecenas sollicitudin, magna quis vestibulum convallis, ligula nulla
fringilla augue, nec rutrum dolor quam vel justo. Vivamus nisi odio,
ullamcorper sed, venenatis id, imperdiet eleifend, neque. Vivamus
justo felis, euismod in, convallis auctor, egestas id, purus. In
rutrum nisi in lectus. Aliquam elementum placerat dui. Integer ut pede
sit amet magna pulvinar placerat. Maecenas massa lorem, lobortis ut,
adipiscing at, suscipit nec, lectus. Curabitur mattis adipiscing sem.
Mauris pharetra vehicula eros. Sed pellentesque elit laoreet augue.
Cras non tellus. Quisque volutpat lectus in sem. Fusce vulputate justo
ut pede. Aliquam ante pede, tempor in, dictum in, blandit eu, sapien.
Morbi vestibulum, metus eu auctor vulputate, nulla lectus condimentum
nisi, ac pulvinar ligula nunc in felis. Curabitur id orci ac est
luctus molestie.