Get in touch with low latency people from Sun, IBM or RedHat? 
jacquesm: Have you ever tried running your low-latency stuff on an environment more real-time oriented ?C on QnX would come to mind a long time before I would start to make anything with those requirements in Java on top of a JVM on a 'regular' (non-hard real time) unix.There are simply too many layers on top of each other to be able to make any hard predictions about worst case latency.I think you picked the wrong tool for the job, and no expert outsider is going to be able to undo the consequences of that decision. You are looking at a fundamental flaw here.On a side note, I do hope that you have at least configured your garbage collector to work incrementally, that will decrease overall performance but it will significantly improve your worst case.