See https://burtleburtle.net/bob/hash/perfect.html

I've written code that, during initialization, after all keys have been collected, essentially called gperf to create the lookup function, compiled it, and then dynamically loaded it, so that the (long-running) program would be able to use it.

Maybe this is one of those situations where compile time code execution wins out. Instead of needing one solution for runtime and one for a priori knowledge, you just run the runtime code during the build process and Bob's your uncle.

I wrote a python library that would build a perfect hash at run-time, it was basically the stupidest way you could do it - it would shell out to gperf to build the library, compile it to a shared library, then link the entry points in (I think with ctypes? I can't remember).

It was just for fun, but in the end even ignoring the startup costs of all of that, the default performance of python's dictionary was better.