Is it faster to use alternation than subsequent replacements in regular expressions

Question

I have quite a straightforward question. Where I work I see a lot of regular expressions come by. They are used in Perl to get replace and/or get rid of some strings in text

Answer 1

First, measure the various options on your real data, because no amount of theory will beat an experiment (if one can be done). There are many timing modules on CPAN that will help you.

Second, if you decide to optimize the regexes, do not squish them into one giant monster by hand, try to assemble the “master” regex with code. Otherwise no-one will be able to decipher the code.