You've done a great first step - getting the thing running before you try to tune it. Doing things the other way around usually leads to putting lots of effort and complexity into the wrong thing.
Ulf's recommendation to hunt down the slow parts is right on. Google for "java performance monitor" and see a variety of tools to help you. JAMon seems to be a very good free one and the author hangs here at the ranch.
A good question is never answered. It is not a bolt to be tightened into place but a seed to be planted and to bear more seed toward the hope of greening the landscape of the idea. John Ciardi
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