GIJOE's Fastest Cache Hack (FCH) provides a much better and faster way of caching Xoops contents. It is per page per module. If you were to modify the templates of a particular module, you would have to wait for the cached contents to expire to get the "new look" of the previously cached contents.
A fast way to expire the cached contents is to delete all the files in XOOPS_TRUST_PATH/fullcache. If .htaccess (usually hidden) shows, make sure you do not delete it.