I don't know the exact specifics here but I know a lot of communities that rank high invest time contributing into the open source Tech Empower tests for their framework. This way they can tweak & make sure their stack runs at optimal speeds.

At the same time, Elixir (and Erlang) are not meant for raw speed. It is best used for real time communication, lots of users & handling errors. At least that is what I have read.