Nowadays, computers are super fast and super huge and super always available.

But even in the early 2000s, that was not the case. I know this b/c one of my first jobs out of college was to build a regex based system to analyze spam emails sent to big providers (like Yahoo and Hotmail (Microsoft)".

IIRC, we only had ONE Dell 2600 box to do all of the above with literally millions of emails and the same box did the parsing and the database storage (via MySql).

You REALLY learn what makes regexes efficient versus not and I remember reading about "/o" and testing it to see if it made a difference for what I was doing. I don't remember either way what the results were but this was def a blast from the past.

PS If you want to read more about the spam work back the, I have a Twitter thread about it here: https://x.com/alexpotato/status/1208948480867127296