It’s very expensive to load configurations and settings from XML files, on every requests.
First because of latency of accessing files from hard drive, second because of the XML
file parsing burden.
Because of that , we implemented in upcoming 1.8 version of DotKernel a cache layer where to store router, acl_role, menu, options(including seo_xml), browser_xml, os_xml, test between requests. More information about the variables which DotKernel cache by default follow this link: DotKernel Reserved Variable Names for Caching