Kirk works for Kodewerk as a consultant offering Java performance-related services and training.
He has developed and tuned applications written in C/C++, Smalltalk, and a variety of other languages.
Kirk has written many articles and spoken at several conferences on the subject of performance tuning.
He helped evolve http://www.javaperformancetuning.com as a resource for performance tuning tips and information.
Recently he founded jClarity which is focused on building better performance diagnostic tooling.