Tuning Java
When we installed Tomcat, we didn't play with the JVM settings. Tomcat's startup script is configured for booting quickly, but of course it can't match all the requirements of the application. Tuning your Java runtime parameters can greatly increase performance. There are many runtime parameters you can set at JVM startup. In the following section you will set the parameters that are most effective on GeoServer performances. Note that the values may vary according to the hardware configuration on your site.
Note
Unfortunately, there is no way to cut corners on the path of tuning parameters for a Java application. While the options presented in this chapter have been widely tested on GeoServer and are recommended by core developers, you should note that the best options may vary depending on your scenario. A valuable resource to understand how each parameter works is at http://www.oracle.com/technetwork/java/javase/tech/vmoptions-jsp-140102.html.