I ran the load tests and couldn't explain it either. I adjusted the thread pools, buffer sizes and a bunch of other parameters and couldn't get Netty to scale.

I think Netty tries too hard to be everything to everyone. This makes it really hard to determine how to configure it properly across a bunch of different versions with lots of incompatibilities.

I wrote java-http with the concept of not doing that. It's purpose built for HTTP and high performance.

Once I have some time, I'll publish my Netty setup and let the community bang on it and see if they can beat my RPS. At 65k, it might be hard though. :)