How to speed up VirtualBox Ubuntu 14.04 (disable visual effects, ...)
If you don't need compositing/desktop effects, then Xubuntu would be the better option.
It has a nice tool in its Settings menu to turn them off, and quite frankly you won't lose anything by installing Xubuntu if you're only going to use it for web/java development. You'll be using the same apps as you would do in Ubuntu.