Is Java really slow?

Answer 1

After reading a page full of comments saying Java is not slow, I just have to answer with a differing opinion.

Slowness of a language is a lot dependent on what your expectations are for 'fast'. If you consider C# to be fast, Java surely is fast too. If your problem domain is related to databases, or semi real-time processing, Java is surely fast enough too. If you are happy to scale your application by adding more hardware, Java is likely fast for you. If you consider that a constant factor speedup in the scale of 5-10 isn't ofter worth it, you likely consider Java fast.

If you do numerical computation on large data sets, or are bound to an execution environment, where CPU resources are limited, where a constant speedup in the scale of 5-10 would be huge. Even a 0.5 speed up might mean a 500 hour reduction for the computation to complete. In these cases, Java just does not allow you to get that last yard of performance, and you'd likely consider Java to be slow.