See the discussion in this Javalobby thread of Wee Jin Goh's recent repeat of the C vs Java benchmark that Chris Rijk published over 2 years ago in this Ace's Hardware article. The latest results show the server version of the Sun JVM 1.4.1_01 on a Windows box doing as well as and even better than C compiled with GCC 3.2 to do the same algorithms. You can find a PDF version of Wee Jin Goh's results here. Another interesting point about the results is the big difference between the client and server versions of the Sun JVM. It would also be interesting to see how the IBM JVM compares on the same hardware. Also, keep in mind that GCC 3.2 is probably producing less optimized code than the latest Intel C compiler produces.