My understanding is that Java is slower as comparision to C/C++. Reasons are being an interpreted language, safety issues etc.
I had read benchmarks comparing Java - MFC - GNU C++ - VB, Java didn't do very well and was last in most of the benchmarks. But I read this benchmark 2-3 years ago, so things should have improved by now
. I don't remember the website where I read this bench mark, but it was a non-microsoft website for sure. If I am able to find it, will post the link again.
But that doesn't make Java any less of a development option. There are many scenarios where I would love to have Java as the solution rather then C/C++.