Q:

Elixir - is there a performance penalty using it instead of plain erlang?

Elixir seems cool but I wonder about the downsides.. if any..
Are there any other potential downsides when choosing it over erlang ?

A:

Elixir reuses most of the compilation stack used by Erlang, so our bytecode is in general very close to the one you would get by compiling Erlang itself. In many cases, it just isn't the same because we include some reflection functions like __info__/1 in the compiled module. Also, there is no conversion cost in between calling Erlang and Elixir and it will never be.

A:

Since elixir compiles directly to Beam bytecode, you don't incure any intermediate costs like a jitter if that's your concern.

