Few comments on the patches.

Just started wondering how much of this slow down is because of MingW libc not having very well optimized memcpy/memmove/memchr/strlen/etc. Is there profiling tools like 'perf' on Linux that could be used for Windows builds?

Problem with SHA-256 on x86-64 is that it took long time for Intel to introduce SHA acceleration (SHA1 & SHA256) to their main CPU products.

Here's fix for mode specific setkey clearing error code:

About error code. You need to use gcry_err_code(error_code) to get the GPG_ERR_WEAK_KEY value.

I'll add documentation about GCRYCTL_SET_ALLOW_WEAK_KEY which was missing from be original commit.

tests/basic now actually fail because setkey not returning GPG_ERR_WEAK_KEY for weak keys with GCRYCTL_SET_ALLOW_WEAK_KEY.

That's right. With GCRYCTL_SET_ALLOW_WEAK_KEY, setkey still returns GPG_ERR_WEAK_KEY when weak key is detected. However, cipher handle can still be used as if setkey succeeded.

Here's mirroring script that is in place currently:

#!/bin/bash -e

Any comments on applying these to gnupg-2.2?

Yep. Closed now.