Not sure that is all of it. You can try turning down the max total memory to eg: 64mb and see what you can still run. An awful lot of stuff just can't, while si

Not sure that is all of it. You can try turning down the max total memory to eg: 64mb and see what you can still run. An awful lot of stuff just can't, while similar applications in conceptually higher level languages (eg: Python, PHP, etc) happily execute. The various factors I see are: - JVM overhead 10-15mb seems to be required just to get off the ground, which directly relates to the JVM replicating a bunch of OS functionality (inevitable tradeoff for portability) - Missing value types - any complex data structure ends up with big overhead from storing references - Stack frames - if you need a lot of threads you need a lot of stack, and a surprising number of threads run Some of this will get addressed in upcoming releases, will be interesting to see how it goes.