Amazing to see the old "C/C++ must be faster than Java because Java is interpreted" myth is still alive and kicking. There are articles going back a few years, as well as more recent ones, that explain with concepts or measurements why this simply isn't always the case.
Current virtual machine implementations (and not just the JVM, by the way) can take advantage of information gathered during program execution to dynamically tune the code as it runs, using a variety of techniques:
- rendering frequent methods to machine code,
- inlining small methods,
- adjustment of locking
and a variety of other adjustments based on knowing what the code is actually doing, and on the actual characteristics of the environment in which it's running.
