It is implemented in hardware on IBM's mainframes, although not upstreamed in the main zlib repo [0]. It gives a massive speedup in my experience up to 20x for

It is implemented in hardware on IBM's mainframes, although not upstreamed in the main zlib repo [0]. It gives a massive speedup in my experience up to 20x for decompression and 220x (!) for compression [0]: https://github.com/madler/zlib/pull/410 https://github.com/madler/zlib/pull/410