You can create a session per process, so you avoid having the session bottleneck. Each session will contain just one process.
I've created a set of tests with the different approaches, but I'm not measuring performance, so I guess that there is a lot of fine tuning to improve the times.
https://github.com/Salaboy/jBPM5-Developer-Guide/tree/master/chapter_11
One important question that I usually ask is: Do you really need to create 2200 process per second? It doesn't sounds like a business requirement from my perspective. Let's say that you are working for a big company that can sell 2200 items per seconds, you are not planning to solve all those cases with just a single machine do you?
Cheers