[OSCache] can really upgrade your performance.  Here's a short HOWTO:

!Install OSCache

''If you are running an older version of JSPWiki, you can skip this phase.  OSCache comes with the distribution.''

Drop the oscache.jar into your WEB-INF/lib directory. 

!Install the tag libraries and properties

''If you are running an older version of JSPWiki, you can skip this phase.  OSCache comes with the distribution.''

Drop the oscache.tld and oscache.properties into your WEB_INF/classes directory.

!Add the oscache.tld to your template

Put the following in your ~PageContent.jsp file (if you're using the default template):
{{{
<%@ taglib uri="/WEB-INF/classes/oscache.tld" prefix="oscache" %>
}}}

!Make JSPWiki use OSCache

Wrap the InsertPageTag with the oscache:cache tags like this:
{{{
<oscache:cache time="60">
      <div class="pagecontent">
      <wiki:InsertPage />
      </div>
</oscache:cache>
}}}

This saves the rendered HTML in memory for 60 seconds.  You can use a longer period, if you wish.  You can also wrap bigger sections of the page, if you want.

!Make JSPWiki flush the OSCache when you edit the pages

Put the following in your ~EditTemplate.jsp, somewhere.
{{{
<%@ taglib uri="/WEB-INF/classes/oscache.tld" prefix="oscache" %>

<oscache:flush />
}}}

!That's it!

Restart JSPWiki and watch those pages fly!

!Caveat

Some plugins (such as the CurrentTimePlugin) will be showing the wrong time, since OSCache will be serving cached versions of the generated HTML.