如何加快javax.json.stream.JsonGenerator的速度？

I'm finally refactoring a restful web service, which yields json output to use an actual json lib, vs manually constructing the json into a StringBuilder and then printing that to the output. Speed is crucial, and currently I'm seeing very poor performance with subject. I have a small benchmark test, where 4 threads are collectively performing ~ 4k requests, and this takes ~5,5s with StringBuilder, and 134s with JsonGenerator. I'm hoping that I've done something wrong. I'm following this guide: I'm finally refactoring a restful web service,