Panama vectors are extremely disappointing. ByteVector.rearrange in particular takes like 10ns and is the only available way to implement vpshufb, an instruction that takes 1 cycle. Operations like andnot don't just use the andnot instruction. Converting a 32-wide vector that the type system thinks is a mask into a vector uses a blend instead of using 0 instructions. Fixed rearranges like packus are missing. Arithmetic operations that are not simple lane-wise operations like maddubs are missing. aesenc is missing. Non-temporal stores and non-temporal prefetches are missing (there is a non-temporal load instruction but apparently it doesn't do anything differently from a normal load, so if you want to move data to L1d skipping other caches you have to use the prefetch).

Panama vectors are still in preview anyway.

Sure, in a few weeks I will post on the mailing list about how lots of stuff one wants to do with vectors is many times slower because of these issues, and we'll see if they end up adding ByteVector.multiplySignedWithUnsignedGivingShortsAndAddPairsOfAdjacentShorts so that people can write decimal parsers or not.

5sec for simple and readable code: https://gist.github.com/corlinp/176a97c58099bca36bcd5679e68f...

Have you seen the 2sec code from c#?

These numbers aren't comparable. This golang solution is likely much more than 2.5x slower if you run them on the same hardware.