Akka-Stream implementation slower than single threaded implementation

Question

UPDATE FROM 2015-10-30

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based on Roland Kuhn Awnser:

Akka Streams is using asynchronous message passing between Actors

Answer 1

In addition to Roland's explanation, which I agree with fully, it should be understood that akka Streams are not just a concurrent programming framework. Streams also provide back pressure which means Events are only generated by the Source when there is demand to process them in the Sink. This communication of demand adds some overhead at each processing step.

Therefore your single-thread and multi-thread comparison is not "apples-to-apples".

If you want raw multi-threaded execution performance then Futures/Actors are a better way to go.