I do quibble with fast, and I also quibble with "dynamic language". Its variables are untyped, but that about ends the "dynamicness" of the language. It's not what people mean.
Elixir is closer, though BEAM in general still leaves a lot of performance on the table. I'm somewhat surprised that tracing JITs and stuff have not managed to make more progress than they have, but it could be lack of developer time. Unfortunately JITs eat that voraciously.
I'd expect this to be a mutable language, though part of that "day one concurrency story" could be an inability to transmit references between something like Erlang "processes".
Elixir is closer, though BEAM in general still leaves a lot of performance on the table. I'm somewhat surprised that tracing JITs and stuff have not managed to make more progress than they have, but it could be lack of developer time. Unfortunately JITs eat that voraciously.
I'd expect this to be a mutable language, though part of that "day one concurrency story" could be an inability to transmit references between something like Erlang "processes".