Some general tips about Java perfomace on Raspberry Pi.
Java loves memory. If you do not plan to use desktop enviroment / XBMC run
sudo raspi-config select memory_split and decrease GPU memory to 16. You'll get more than 100 Mb of additional system memory.
Do not swap! Manage your JVM memory consumption with
-mx keys. If you absolutely have to swap move swap file (/var/swap) to USB HDD of fast flash drive because swapping to SD card is painfully slow. You can set swap size in /etc/dphys-swapfile config file.
Consider CPU overclocking with
sudo raspi-config for considerable performance boost.