tl;dr

Use memory mapped files to "talk" between processes. Use flyweights for the messages. Avoid strings in the messages wherever possible. Use single-threaded processes wherever possible. Isolate cpus. Pin to isolated cpu. Turn off hyperthreading. Use some form of object pooling.

The last point is the only Java/GC language specific thing.

Having used Chronicle I can confirm that you can see single digit microsecond latency (or better), and reduce 99th percentile jitter with significant analysis.