There are a few things you can try:

(?:thing){0} seems to be a poor man's comment. I'd use an ordinary #...\n comment instead, or (?#...) comments.

Second thing: split on whitespaces as far as possible, and then check the individual fields with anchored regexes

You can also use (?>...) non-backtracking groups for things that don't have to backtrack. That will make regexes fail faster if they can't match.

If you have the choice, use perl 5.10 or newer, it has a an awesome optimization for alternatives of literals.

In reply to Re: How do I optimize a regular expression? by moritz
in thread How do I optimize a regular expression? by kyle

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