Is Java really slow?

Answer 1

The major problem with java applications is that it is huge due to the large size of the stock runtime library. Huge programs fill a lot in memory and tend to swap, meaning they become slow.

The reason the Sun JVM is large is because it has a very good byte code interpreter which works by keeping track of a lot of things. That means much data, which means memory.

You may want to look at the jamvm virtual machine which is an reasonably fast interpreter (no native code) and very small. It even starts up fast.