C performance vs Java C

Question

can anyone explain how it is possible for one of the virtual machine languages perform better than a native language?

Answer 1

Generally, C# and Java can be faster because the JIT compiler -- a compiler that compiles your IL the first time it's executed -- can make optimizations that a C++ compiled program cannot because it can query the machine.

A C++ program has to be compiled beforehand usually with mixed optimizations so that it runs decently well on all machines, but is not optimized as much as it could be for a single configuration (i.e. processor, instruction set, other hardware).

Answer 2

• The overhead of interpreting code is much higher than 10-15% (I'd guess at along 3x-5x or higher). In order to get down to 10-15% you have to use some form of machine-code compilation step (i.e. JIT). (Try running a JVM with JIT switched off, and you'll see the performance drop like a rock.)
• Garbage collection does have a performance impact, but I'd say that everyone agrees that it is worth it. If you can afford the byte-code compilation/interpretation overhead, you can afford the gc overhead as well.
• Socket programming is much easier in Java than in C/C++, if that's what you're asking. And performancewise, the socket I/O overhead dominates over the Java execution overhead.
• Most modern JVMs have true threads, i.e. each Java thread is executed by a kernel thread, allowing Java threads to utilize modern multi-core CPUs.