Only if it's backed by security-reviewed and fuzzed asm. Go's gzip implementation is slow enough that klauspost is worth importing, following that pattern, I would probably still use klauspost's zstd even if Go had a slow reference implementation in the standard library.
What I'm really hoping for is something as seamless as gzhttp but for zstd. https://github.com/klauspost/compress/tree/master/gzhttp