Both Netty and Play use Jackson though one the Netty version uses a single ObjectMapper and the Play version uses a new ObjectNode per request (created through Play's Json library).

No, they use Play's JSON lib. It's kind of a moot point because Play's lib is in fact a wrapper for Jackson.

Here's the source: https://github.com/TechEmpower/FrameworkBenchmarks/blob/mast...

So the question stands: If Play & Netty are using the same JSON serialization code, why is Play seven times slower?