Though, if you manually try to check the VM (i.e. execute 'java -version') of the JVM that SiteVision runs in you get different results ('Server VM' or 'Client VM') depending on the hardware of the machine. This is due to a feature introduced in Java 5.0 called Ergonomics.
More information about how to enable portlet caching can be found here.
Note that caching is not used when you are editing (offline mode or editing mode). The cache is filled on the first request in the online mode (visitor mode).
<%@ page contentType="text/html;charset=UTF-8"%>
Note that any internal JSP portlet uses UTF-8 and must have this attribute set.
If your JSP portlet includes other resources like HTML jasper might behave strangely (sometimes assuming UTF-8 and sometimes ISO-8859-1) with resulting encoding problems. To solve this issue alter the extention of your HTML file to jsp and add the page directive specified above.
The java files generated by jasper are located in the working directory of sitevision.
.../data/temp/work/...
More information is available on the Public API page.
(SiteVision uses Axis for the XML import Web Service, but the Axis JAR can not be accessed/loaded from within a custom portlet.)
The page published: