Memory allocation and scheduling are both important considerations but are separate problems. BEAM concurrency only involves memory allocation when the process

Memory allocation and scheduling are both important considerations but are separate problems. BEAM concurrency only involves memory allocation when the processes are created. Switching between them doesn't involve allocation and is very quick (don't forget we are talking about BEAM processes here not OS ones - it's all in userspace and very efficient). As long as you pre-create your pool of worker processes concurrency doesn't incur much allocation hit. You're right that immutability might do though. I am curious to see how this goes - the speed that Elixir normally runs at combined with some data sharing optimisations means that this issue doesn't exist normally. At the speed we care about when doing numerical work it's more of a concern. Or maybe we'll never get into the realms of full optimised C++ where things are sized for cache lines etc. (and that's ok).