I love everything about this project, but I am fairly skeptical of their benchmarking. In particular, they use a _lot_ of polynomial intervals for some of these

I love everything about this project, but I am fairly skeptical of their benchmarking. In particular, they use a _lot_ of polynomial intervals for some of these functions, it's easy to accidentally construct microbenchmarks that miss the cache effects that fall out of that (the full set of coefficients for one of these math functions can easily take up a substantial fraction of your L1; for some use cases that won't matter, for some other scenarios it will be catastrophic). Historically, high-performance libm implementations have gone to great pains in their internal benchmarking projects to avoid accidentally ignoring these effects and shipping functions that are significantly slower in real use. None of this is to say that they have necessarily fallen into this trap, but historically most "fast" math function implementations that use piecewise polynomials with high segment counts do (and none of it should take away from the accomplishment--even if they're really 2x slower than claimed, they're fast enough for most code to simply use it unconditionally and get the portability benefits).