[_investigator]

tl;dr

The original basic RE and extended RE (when backreferencing is not used) are significantly faster than implementations that most programmers traditionally rave about, e.g., Perl RE.

Tell me something I didn't know.

He thus used such 30 year old code as a model and easily topped the speeds of the built-in RE capabilities of today's popular scripting languages.

Common sense is underrated.

[rsc]

Wow, everyone's a cynic. Did you miss the part about the trigram index?

It sounds like you are replying to regexp1.html, not regexp4.html.

[_investigator]

No. You misread. I love Russ Cox's way of thinking and his continual generosity in sharing his work. I too use the Plan 9 base sed and grep. I'm cynical about the people who rave on about perl/javascript/python/ruby/whatever regexp, who derive some perverse joy in ridiculously complex RE and who often diss sed and all things old school as being slow or deficient in some way.