Quoting Nate Bargmann (n0nb@???):

> I'll admit, there was one trick that SD did that I liked, and that was
> starting CUPS only when there was a call to print. I don't print often
> so bringing up CUPS on demand and then shutting it down later was nice.
> But then, SD was running all the time, so not much was gained.

CUPS is almost the only game in town, but there was a project I long
admired a great deal, that ran a very lightweight print subsystem with no
queuing, called PDQ (print, don't queue). It's been unmaintained for
quite a few years, but is probably still practical. Because it has an
interface to Foomatic, it supports all printers that work under CUPS or
LPRng. (It still runs a daemon process but it's a small, simple one.)

http://pdq.sourceforge.net/introduction.html
https://sourceforge.net/p/pdq/news/2006/06/resurrect-pdq/