The point was that it kills parallelism – Node is just a single-threaded event loop, running on a single core. And since computing fibonacci numbers is a CPU b

The point was that it kills parallelism – Node is just a single-threaded event loop, running on a single core. And since computing fibonacci numbers is a CPU bound activity, that type of benchmark would be relevant but for the memoization bit. EDIT: Well also, the author would have to actually benchmark this vs. Node with many concurrent clients in order for it to be relevant; here he's just timing a single request from start to finish, which obviously doesn't say anything about how this scales.