So now we're not just comparing optimized erlang to unoptimized C, but optimized erlang doing X to unoptimized C doing Y. You can write the wrong code in erlang too, C does not have any special (mis)features that encourage doing the wrong thing. It dishonest to say "erlang isn't slow" and use "I can write slower C code if I do it on purpose" as evidence.
The thing is that "slow" is naturally relative. I hate it when people claim that a tool is slow. By far the most important factor in getting programs that work isn't the technology but the mind behind the code. This is true for any programming language.
I guess the succinct answer is: No, Erlang isn't slow if you know what you are doing, barring the Caveat about CPU-bound problems. The message I am trying to convey is that there is more to fast programs than the execution speed of the technology at hand. It is a factor, admittedly, but it is not the sole factor.
