Did you compare performance to SHA512? Despite being a theoretically more secure/"harder" algorithm, on 64 bit platforms it can sometimes be faster than SHA256. If you don't want to use 512 bits, using 256 bits of the output of SHA512 is standardized as SHA512/256 and is considered valid/secure.
(I'm unclear if this performance oddity remains true with the crypto hardware extensions being used here.)
For comparison with other checksums you should look here
https://github.com/minio/sha256-simd#comparison-to-other-has...
SHA-512 should be much faster than SHA-256 on AVX2-capable processors. Go's implementation is subpar; try OpenSSL instead. On Skylake, SHA-512 is about as fast as MD5 now -- https://bench.cr.yp.to/results-hash.html#amd64-skylake
Yes true. OpenSSL version gives a great boost. Rather than SHA512 we ended up using Blake2b - https://github.com/minio/blake2b-simd (also optimized with SIMD instructions) internally for bit-rot verification in https://github.com/minio/minio