How to achieve maximum single threaded performance?

Interesting. But I’m not sure if MC is that IO dependent, I ran a nice modpack server off an HDD a long time a while ago. Linux VFS should take care of it.

even before they did that and I wasn’t aware either, it uses your other threads a bunch too as the trashing of the heap makes the GC busy

Perhaps the default GC was improved. With no GC config and the pause interval you can easily get a seriously stuttery server when exploring a huge cage complex, I remember. Enemies would pause and teleport making it a lot harder to fight them. A good benchmark I’d say. For OpenJDK8 I used something like this: -server -XX:MaxGCPauseMillis=50 -XX:+DisableExplicitGC -XX:+UseG1GC

Apart from disabling SMT benefitting singlethread performance, I am not sure. I thought idle cores lead to more power available for busy cores.

Anyway wish you success in building that server.