There is open source for bzip2 v1.0.3 at http://www.bzip.org/downloads.html. I felt a little bit slow to compress 10MB file on my Intel Pentium 4 machine. I modified some source code and recompile, then get 20% speed-up...really exciting!!!
Know more detail to see http://www.linuxforums.org/forum/comments-feedback-suggestions/70083-bzip2-increase-performance-traditional-linux-utility.html, and welcome to raise any question to me.