If you're at a scale at which you're seriously using Erlang, "fast" isn't really a concept that applies anymore. You really end up with "enough performance" or "not enough performance", with an at-times surprisingly sharp transition from one to the other, and while the base performance of the underlying language is certainly a major factor in whether you have "enough", it isn't the only factor, or even necessarily the most important. (Which is good for Erlang, because it's actually quite slow at most conventional things.) It doesn't matter if I've got "sub-millisecond message processing" if I'm trying to run more messages through a box than it can handle, or if I've got an external response handler that sometimes clogs up.
There's no way that Erlang can possibly be "fast" enough that somebody won't throw a task at it that's still a performance challenge.