"This implementation" is notqmail, which none of the netqmail people are involved in.

netqmail 1.06, which none of us notqmail people were involved in, was produced by a handful of people I have often referred to as "list elders". They were very informed, very conservative, and very careful.

Nothing wrong with heuristics. It's a busy world out there. I appreciate that you're aware you're using one here, and I thought you might like to know it's led you astray. As a notqmail developer, I hope we live up to the standards set by the netqmail folks.

Does using warez slang automatically make software less secure and slower?

It reduces confidence because warez is associated with running cracked software of which you don't know exactly what was modified/added/etc.

My how far we’ve come in such a short few years.

Eh, not sure what you mean, but yeah some DRM is obnoxious and almost spyware. Warden, World of Warcraft's DRM, is for example profiling your system hard.

It speaks to the priorities, attitude and / or the work ethics of the developers involved. I wouldn't trust people who care about using teenager slang and looking cool to write secure and efficient services that I could use in production with customer data. I may be wrong, but my confidence is still low.