Note: this is using AVX512, and in current Intel processors that have it using it will downclock all of your cores, which might be worse in tje end for your performance.
The authors address this concern in passing: they haven’t observed any downclocking. It’s also worth mentioning that they only use the vpermb and vpmultishiftqb instructions, which according to this shouldn’t be that worrisome. In the link vpermb is mentioned explicitly, but vpmultishiftqb isn’t.
Where is this useful? Only thing that I can think of is MIME processing. Who else is using base64 in such a degree that it warrants this much optimization work? :)
Binary data in JSON. It’s evil, but sometimes it has to be JSON.