I keep running across pieces like this DeveloperWorks article called Java theory and practice: Urban performance legends revisited, discussing the performance benefits of Java – that it is in fact faster than C or C++.

The article makes some convincing arguments. In fact most of the arguments I hear are convincing. However, performance of real-world java apps still leaves a lot to be desired, and certainly is leagues behind C/C++ apps.

I’ll give you an example. I’ve personally been involved in two projects that essentially involve creating a Web proxy that does various fancy things. One version in Java, the other in C. The Java version tops out at maybe 200 simultaneous requests per second, while the C version is somewhere above 1000/sec. The Java version is actually a second generation, optimized rewrite of an earlier Java version that brought about significant performance improvements. Still, it lags far behind the C version.

You can try this yourself. Grab Axis and gSOAP. Write a simple service in each. Now throw load at them. Lots of load. You’ll see the same thing: gSOAP will be many times faster than Axis and handle much more simultaneous load.

Perhaps Java is very fast but people tend to write slow, inefficient programs with it? I have a theory that the fact that it’s easier to write code in Java than C leads people to write more code than they would in C to do the same function, which ends up causing bloat and slowness.

I don’t have a religious axe to grind here – I’d be very happy if Java was in fact very fast. However, pretty much everything I see in practice points to Java being much slower than C/C++. What’s your experience?