#!perl

use strict;
use warnings;

use Benchmark qw( cmpthese );
use English qw( -no_match_vars );

local $OUTPUT_RECORD_SEPARATOR = "\n";

print 'Perl version: ', $PERL_VERSION;

my $s = 'Aid bears out ' x 10_000;

print 'Length of string: ', length $s;

cmpthese( -1, {
   'lc'       => sub { () = lc($s) =~ m{ [aeiou][aeiou]           }xmsg },
   '[Aa][Aa]' => sub { () =    $s  =~ m{ [AaEeIiOoUu][AaEeIiOoUu] }xmsg },
   '[Aa]{2}'  => sub { () =    $s  =~ m{ [AaEeIiOoUu]{2}          }xmsg },
   '/i'       => sub { () =    $s  =~ m{ (?i) [aeiou]{2}          }xmsg },
} );
__END__

##</code><code>##

Perl version: v5.12.0
Length of string: 140000
           Rate  [Aa]{2}       lc [Aa][Aa]       /i
[Aa]{2}  50.7/s       --      -0%      -1%      -3%
lc       50.8/s       0%       --      -1%      -3%
[Aa][Aa] 51.5/s       1%       1%       --      -2%
/i       52.5/s       4%       3%       2%       --