I find this dubious -- I think the last parameter (`mitigations=off`) does the job they're after.

Regardless, I'd expect a small/difficult-to-discern improvement in practical use-cases. Caveat: on relatively recent chips. Many-generations old i3/i5 chips with none of these mitigations in hardware probably are suffering.

I'm sure synthetic `openssl` benchmarks are favorable, but I don't use my computer for that

If you're churning enterprise data, sure, it might be meaningfully quicker - but good luck convincing auditors that was a good idea.