Typically regex parsing isn't benchmarked thoroughly, so you probably won't get any solid answers to your query. The reason why it isn't benchmarked thoroughly is because it's generally fast enough, and is typically dwarfed by other aspects of the regex compilation phase. (Which in turn varies with the regex engine, and depends on how much analysis it does up front. Some do very little, some do a lot.)

This is both a regex parser and a regex matcher, and I believe fao_ meant the matching part.