I would argue that at least for client-server apps Erlang is faster. Here is why: in most cases the perceived performance of a server is constrained by maximum

I would argue that at least for client-server apps Erlang is faster. Here is why: in most cases the perceived performance of a server is constrained by maximum (or 99%, whatever) latency, not by throughput. Moreover, you can scale throughput horizontally, while scaling for latency is more or less impossible. Haskell's GC can give you horrendous pauses (see [1][2]), ruining perceived performance. Erlang, on the other hand, is thoroughly optimized for minimal latency. TL;DR: "fast" isn't well-defined, and for a lot (or even most) applications "fast" is about latency, not throughput, and Erlang is "faster" in that sense. [1] https://making.pusher.com/latency-working-set-ghc-gc-pick-two/ https://making.pusher.com/latency-working-set-ghc-gc-pick-tw... [2] they eventually abandoned Haskell for Go https://making.pusher.com/golangs-real-time-gc-in-theory-and-practice/ https://making.pusher.com/golangs-real-time-gc-in-theory-and...