2.2.3 was released yesterday: https://github.com/zlib-ng/zlib-ng/releases/tag/2.2.3

New Years release, zlib-ng's 10 years celebration

My first commit in this repo was in October 8th 2014, although I do remember that I started during summer vacation and had made the zlib cleanup more of a mess than I wanted, so I restarted from scratch in October when I had gotten a better overview of the code and what I wanted to do to clean it up. At that point zlib-ng was not very likely to go anywhere, but despite the odds, over time several people found it and opened PRs with their own improvements, a few of those became long-time contributors, and a few years ago zlib-ng finally became more than an experimental fork. Zlib-ng has since gained traction and several distros have started replacing stock zlib with zlib-ng in compat mode.
...

🎉

Release 2.2.3

...
It also contains several optimizations. Especially of note, inflate has been optimized on various instruction sets and also the generic C code has seen improvements, and we have improvements for arches where unaligned accesses are not possible (lacking instructions to handle unaligned access) and also improvements on big endian.

Example benchmarks:
x86-64 AVX2: Inflate ~17.8% faster, Deflate unchanged. -4.6KB library size.
Aarch64: Inflate ~2.3% faster, Deflate unchanged. - 5.5KB library size.