Erlang's inter-process messaging is ridiculously optimized. Processes are extremely low-weight, it costs approximately nothing to start and stop them. This is one of the core strength of Erlang.
Running one process per neuron would actually be a very efficient way to do it.
I'm quite sure that would be a grossly inefficient approach. Sending a message is expensive in Erlang, less so than in other languages, but it's still very large compared to a few math operations. It's a common mistake to use processes to represent objects [1].
The recent article from Discord [2] also mentioned "Sending messages between Erlang processes was not as cheap as we expected, and the reduction cost — Erlang unit of work used for process scheduling — was also quite high. We found that the wall clock time of a single send/2 call could range from 30μs to 70us due to Erlang de-scheduling the calling process."
