Sorry but everything is relative and we could have just stick with JVM and Java as it's super performant and you have enough developers to choose from.
Picking elixir over ruby is like picking a katana when you want machete.
"Perfomant" is very relative if I care about worst case latency BEAM outperforms JVM. Elixir is about as productive as Ruby yet about 10-15 times faster. To me BEAM/OTP's features more than make up for the slower number crunching performance compared to JVM.