A dying art? Yes and no... There have been quite a few recent articles posted here about squeezing the maximum performance out of compression algorithms, say, by clever use of SIMD operations.

It’s certainly less common now to be quite so concerned with shaving individual bytes off the code size. But I bet that still comes up when generating function prologues/epilogues/trampolines etc in compiler output -- stuff that will appear a lot in the output, so even one word saved will be significant.