So, the zstd executable links to libz.so (says ldd), and I don't think it reimplements the core algorithmic part of gzip. I gather that it's simply more intell

So, the zstd executable links to libz.so (says ldd), and I don't think it reimplements the core algorithmic part of gzip. I gather that it's simply more intelligent in how it uses the API... e.g. it says some things about reusing contexts, though that seems to apply only to handling multiple files.