I've had a report (from Matthew Kempe) about another problem with the openssl benchmarking code. It fails on FreeBSD, because there (and possible in other environments too) openssl has been configured without RC4 (aka arcfour) support. I'm considering just deleting code to benchmark openssl arcfour; I don't plan any improvements of Nettle's arcfour performance, and I would be surprised if the openssl people do.
I do intend to keep arcfour support in Nettle for the foreseeable future, to support old protocols and applications. But I'm thinking that maybe the arcfour assembly code could be deleted?
Nettle currently includes arcfour assembly implementations for x86 (32-bit) and sparc (both 32-bit and 64-bit), which as far as I remember gave a modest speedup when added. But the code hasn't been tuned or benchmarked recently. And we have nothing for more relevant platforms.
Regards, /Niels