> Performance wise... The SHA series have hardware acceleration on
> modern CPUs and SoCs.  External libraries such as OpenSSL are in a
> position to provide implementations that make use of that. Same with
> the Linux Kernel CryptoAPI (https://bugs.python.org/issue47102).
>
> Hardware accelerated SHAs are likely faster than blake3 single core.
> And certainly more efficient in terms of watt-secs/byte.

I don't know if OpenSSL currently uses the Intel SHA1 extensions.
A quick google suggests they added support in 2017.  And:

* I'm using a recent CPU that AFAICT supports those extensions.
  (AMD 5950X)
* My Python build with BLAKE3 support is using the OpenSSL implementation
  of SHA1 (_hashlib.openssl_sha1), which I believe is using the OpenSSL
  provided by the OS.  (I haven't built my own OpenSSL or anything.)
* I'm using a recent operating system release (Pop!_OS 21.10), which
  currently has OpenSSL version 1.1.1l-1ubuntu1.1 installed.
* My Python build with BLAKE3 doesn't support multithreaded hashing.
* In that Python build, BLAKE3 is roughly twice as fast as SHA1 for
  non-trivial workloads.