Any suggestions to tune this?

Cool. I can offer a suggestion that uses a module I wrote. Regexp::Assemble is designed to optimise expressions like this. Consider the following:

use Regexp::Assemble;

my $r = Regexp::Assemble->new;
while( <DATA> ) {
    chomp;
    $r->add( $_ );
}
print $r->as_string;
# produces ^(?:K[LM]|P[AM]|S[LZ]|CP|ME|WX|YZ)XX1

__DATA_
^CPXX1
^KLXX1
^KMXX1
^MEXX1
^PAXX1
^PMXX1
^SLXX1
^SZXX1
^WXXX1
^YZXX1

[download]

You can also do this as a one liner:

print Regexp::Assemble
    ->new( chomp=> 1 )
    ->add( <DATA> )
    ->as_string;

[download]

The other thing you can do is take the assembled expression, remove the ?: to turn it into a POSIX-compatible expression, and feed that to egrep. (see Aristotle's words of wisdom below).

update: hmm, I see that this produces the same thing that other posters have done by hand. Bear in mind that R::A is more at home when dealing with hundreds or thousands of discrete expressions: that is where it starts to shine. With 10 expressions it's like a car in first gear. Still, if your real-world environment is using more than you show here, you will see a definite improvement.

Another thing it's good at is when your expressions aren't so, um, regular. Consider what happens when PMXX1 is changed to PMXX2. (Hint: ^(?:(?:K[LM]|S[LZ]|CP|ME|WX|YZ)XX1|P(?:AXX1|MXX2))). That's not quite as easy to work out by hand.

- another intruder with the mooring in the heart of the Perl

In reply to Re: perl performance vs egrep by grinder
in thread perl performance vs egrep by dba

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