which gives you the efficiency of performing a single match,
A single match is not always more efficient. A bunch of simple matches can be more efficient than a single, more complicated, match. And that's because of the Perl optimizer. Here's an example: 
#!/usr/bin/perl

use strict;
use warnings;

use Regexp::Assemble;
use Perl6::Slurp;

use Benchmark qw /cmpthese/;
use Test::More tests => 1;

our @data = slurp '/usr/share/dict/words';

our(@a, @b);

cmpthese(-10, {
    regex => '@a = grep {/qu/ || /x/} @data',
    ra    => 'my $re = Regexp::Assemble->new->add("qu")->add("x")->re;
              @b = grep {/$re/} @data',
});

is_deeply(\@a, \@b);

__END__
1..1
        Rate    ra regex
ra    4.71/s    --  -65%
regex 13.5/s  186%    --
ok 1

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In reply to Re^2: Regex and question of design by Anonymous Monk
in thread Regex and question of design by amaguk

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