Can I rephrase the question?

How much concurrent tasks can you run on a mid sized server in 2024?

Definition of mid size: machine that will have 1TB Ram and maybe 64 Cores.

A small machine would be my workstation. 192GB Ram and 32 Cores.

What programming env do I have to use to eat up all those Ressources without petering out?

Isn't this the task Go was built for? I'm surprised it faired so poorly.