[jules]

I guess, but in my experience optimization buys you maybe 2x if the code was written reasonably well. By using Erlang you leave 3x-30x on the table vs reasonably well written C, and it's often easier to write that C code than to optimize the heck out of code in a slower language which ends up being 3x-30x slower anyway. On the other hand Erlang is an excellent choice for distributed systems that are latency bound.

[simoncion]

If you've decided that Erlang is the right system to use, isn't it good to know how to -when needed- design the fastest Erlang code possible?

The existence of another language that creates faster programs doesn't make the task of optimizing software written in the slower language irrelevant.

Make sense? :)

And, I mean, languages like Erlang make writing software to solve certain classes of problems far easier than if one were using straight C. What's more, Erlang lets you plug in code written in other languages, so you can keep the very logically tricky stuff in Erlang, and do the perf-critical stuff in -say- C.

[jules]

I didn't say optimizing Erlang is irrelevant, just that for me a book about optimizing Erlang is less relevant than a book about writing distributed systems in Erlang.