> Would you say then that Erlang has low latency and low standard deviation of how fast it will respond to any request under any amount of load.

Yes, that's exactly correct. Erlang/Elixir server apps aren't the fastest around but their latency is very predictable and they remain responsive under load, unlike programs written is most other languages.

That's the main selling point of the BEAM VM.

I'm not the best person to ask about Erlang's performance characteristics. I know them in broad strokes from light reading about the BEAM VM but I've never written any Erlang that has made it out to production, only for the smallest of hobby projects. So I don't know, e.g. what the P99 latency of a given Erlang program might be.

That being said, my point was that concurrency is an independent topic from runtime performance (including latency), which is the domain of parallelism. Erlang's big selling point is it makes it possible to write concurrent programs whose functionality (not performance) would require oodles and oodles of code and discipline in some other languages.

EDIT: On reflection I do think if what you're talking is catastrophic latency overruns caused by cascading queuing failures then Erlang can indeed help make it easier to avoid those pitfalls.