The OP (Original Post) showed 2 lines of code. Neither one of which tallied the number of substitutions properly. My examples showed how to tally that for an individual line in very explict terms as I thought that was the "problem".

Both of your OP's example lines contain a "foreach" loop. "for" is just a shorthand for "foreach". "map" is a kind of a foreach loop. My post and Limbic~Region's are similar in advice. "A foreach is fine", means that you save nothing by "disguising" the foreach by writing it on a single line. The "foreach" is still there.

Are you saying that a foreach loop would be just as fast as what Limbic-Region was suggesting for an array? Limbic~Region's "for" statement IS a "foreach loop".

The OP didn't mention anything about running 10K regex'es on 30K lines! Although, it sounds like from subsequent posts that you have a solution that meets your needs in terms of performance. I don't really understand your application, but if this is some type of word for word substitution situation, a hash based approach would be faster. But that is mute if you are happy with what you have.