Java Runtime Performance Vs Native C / C++ Code?

Question

I\'ve become more and more comfortable programming in Java than with C++ or C. I am hoping to get a sense of the performance hit incurred using a JVM interpreter, as oppose

Answer 1

Actually, a VM can do a lot of optimizations at runtime, based on information that's only available at runtime, that a C/C++ compiler cannot do. So, in most circumstances, the JVM will be at least as fast as a native program.

Brian Goetz answers most, if not all of your questions in his talk Towards a universal VM.

Answer 2

Important thing to note down is

Java byte code JIT compiled to much more optimized code specific to particular hardware

vs

C code compiled and optimized to general hardware so it cannot take advantage of features provided by specific hardware

Answer 3

Both java and c# (and objective-c) are not nearly as fast as native code can be. But that only matters if you have a problem where you are not engineering-time limited. Because you'll have the time to devise a better algorithm with a high level language.

So basically, if you're developing a device where you're going to build a million a year of, or that is battery powered, you don't use java or c# to build its core functionality. You might add a lisp interpreter to make customisation easy, though. Microsoft is not going to use c# for say the core of SQL server, where performance really matters. Visual Studio on the other hand, where MS can expect users to have high-end hardware, can be used as a showcase for slow but high productivity technology.

Please note that I currently do most of my programming in Pharo Smalltalk, which is a lot slower than java, c# or objective-c, and is not even one of the fastest Smalltalks. Productivity trumps performance.