Provide automatic keepalive for certain groups, and session timeout notifications for everyone else.
YSlow and Pagespeed look at Expires Headers when evaluating your site. This plugin allows an administrator to set global Expires, Cache-Control and Pragma headers, as well as individual settings (inclusive or exclusive) for particular menu items.
Your Joomla /administrator area is vulnerable to many forms of attack. Without protection, anyone can begin a brute force attack by simply typing "/administrator" - That's too easy!!
Keep honest people honest, and keep everyone else OUT! Secure your site with AdminExile