[acqq]

The tests here confirm your experience, Erlang is for many algorithms significantly slower, even when more cores are used:

http://benchmarksgame.alioth.debian.org/u64q/erlang.php

[digitalzombie]

Do not use Erlang for number performance. I tried with EulerProject and create some prime number generators in Erlang. It is slow as hell.

Use it for what it is built for!