Amazing thread! Just found it, and I am amazed I didn't find it earlier. It would have saved me some money in setup fees and hosting for testing different servers.
I have never updated clock speeds manually or optimized the OS.
However, I tested most VPS and dedicated servers available around five months ago and found that the Hetzner AX102 with Ryzen™ 9 7950X3D had the best PHP raw performance of all (with a normal install, nothing tweaked) and very good stability.
I also tested Runcloud on the same server, and it has a worse performance than Enhance. I used Runcloud before switching to Enhance.
I am now looking for a new alternative with AMD Ryzen 9 9900X - maybe Hetzner will offer these soon. This launched about 1 month ago or so.
Also, what do you think? Should I try to tweak my OS/CPU, or whatever it's called, to increase raw performance? Is it worth it? Does it come with any drawbacks or stability problems?