Lets say my friend needs to write an incredibly math heavy application. He has thought about using C++, but he wants to write it in Java. Just how slow is Java compared to C++? His application will need to solve something like a 10000 by 10000 matix per frame, so performance is important. What should I tell him? Make it in Java or C++? And why?
(He really really wants to use Java, but if the application is going to run at snail speed, he's going to be extremely disappointed.)