There are lots of issues to be adressed when talking about the speed on languages. I've seen tests on primitive types that showed that Java and C++ were about equally fast. But when it's a complicated program like a chess engine things are different.
I saw that Dr. Oliver Brausch has source code to his engine OliThink in both C and Java on his homepage, if anyone would like to compare...
Java has an excellent profiling option:
e.g. -Xrunhprof:cpu=samples,heap=sites
that allows you to identify the bottlenecks of your Java program.
There are also programs available to organise the and view the often huge output file easy.