I have made a couple of speed improvements to the core geeklog files. The modifications are in system/lib-security.php (SEC_getUserGroups and SEC_getUserRights) and public_html/lib-common.php (COM_exportRDF and COM_rdfUpToDateCheck). I welcome any input/evaluation people have about these changes.
More information about these changes, and links to the source, can be found at furia.abtech.org.