Thanks /Ole
As mentioned before, we're not sure if it is the Mockservice that is the main source of the problem. All I'm after is some benchmarking that might have been done.
The mockservice is very simple and returns a static response with a Sequence dispatch type.
The Mockservice is indeed very fast when sending sequential requests and to simulate backend processing we've added a response delay of 500ms.
Problems occur when performing a ramp up test up to 24 simultaneous users up to a total of 120 requests per second.
It might be the number of simultaneous connections to jetty, or some other network setting we're not aware of.
We have implemented a simple webservice to do the same task running in WebSphere and it is handling the requests fine.
Kind regards.