If your Joomla site is taking a while to load the Joomla application base may not be set to cache it's functions. The file caching allows the system to find a certain page directly from hard disk and removes the delay induced by a MySQL query to retrieve the same page in the database. The speed of page loading will also be increased by enabling caching. Please reference the tips on the site below to enable caching on your Joomla site.
http://news.softpedia.com/news/Tips-to-Improve-Joomla-Performance-63108.shtml
