[exposition]

Yep the standard I refer to is Info-ZIP (zip(1)).

I will add the resulting compression sizes- there is not much between them (pzip was around 2% larger for the 10GB directory). Although, I do have some optimizations in mind which will bring this down further.

[acqq]

Allowing for 2% bigger resulting file could mean huge speedup in these circumstances even with the same compression routines, seeing these benchmarks of zlib and zlib-ng for different compression levels:

https://github.com/zlib-ng/zlib-ng/discussions/871

IMO the fair comparison of the real speed improvement brought by a new program is only between the almost identical resulting compressed sizes.