You'll like this video. This guy uses lots of optimization techniques to get a PHT that runs more than twice as fast as the gperf one (the best one he found that isn't specifically constructed) https://www.youtube.com/watch?v=DMQ_HcNSOAI
I'm currently looking at BoomPHF which seems faster than the last time I did a MPHT https://github.com/10XGenomics/rust-boomphf https://github.com/rizkg/BBHash
great video
they have butts