> handle communications within dozens of nanoseconds. So its a bad "emulator" for SuperComputers

But ping on local host reports .3 ms latency..?

In any case it’s still an easy way to get started, and arguably when exact latency starts counting for something, you have to be tuning your code on the system it’s going to run on. An RPi cluster could skew that in all sorts of ways, eg the TCP stack being disproportionately slower etc