You have a basic system installed and your open simulator servers are working quite right. And now what?
You could learn about "power configuring" unga here.
Changing some parameters on the system could improve the performance. Read it here.
What about using a No-SQL and distributed storing system? Read it here.
Improving the performance of the web servers. Read it here.
Using web server clusters.
And the final step is to program your own plugins of modifying unga core. The secrets are here.
Up, up and away!