Why Pure Swift Beats ARM Hardware CRC32 Instructions

After publishing Can Swift Match Rust on a Lambda Micro-Benchmark? I got a wave of questions about one specific result: the CRC32 decision. People couldn't believe it. Fair enough. I wouldn't have believed it either before measuring. The question that kept coming back, from a thread on Mastodon : "I didn't know ARM had dedicated CRC instructions. Is it slow because you're on a vCPU? Would it be…