Speed a little too slow seems to be.
AMD 9950X with 32 threads, here 24 active.
It would be awesome to make Cyclone work on cloud server with 192 threads!...
I know there are other versions on github but they don't have random mode.
I achieve 40M keys/s, but after 25 minutes, it drops to a constant 37M keys/s. Is this normal on AMD?
I think he already has AVX-512, but he hasn't published it on GitHub yet. There are pictures of his screen showing 128 cores

The performance drop you're seeing (from 40M keys/s to 37M keys/s) is pretty normal, depending on your system setup and workload.
After 20 minutes of non-stop running, your CPU might heat up and trigger thermal throttling, which causes a slight slowdown to keep things cool.
Yeah, I have the AVX-512 version, but it's even worse. If you're using a dedicated machine (like a root server), this aggressive script could totally fry the CPU because they usually have tiny stock cooler.
That's why I'm kinda iffy about uploading it I don't wanna be on the hook if someone melts their $7-8K processor.
P.S. Cloud servers usually don't give full physical access to hardware youll never hit max speed. Plus, they'll kick you out of there pretty quickly.