We wrote a Joomla and Virtuemart cache plugin which works similarly to "system - page cache" plugin but supports Virtuemart caching as well. Default core page cache plugin cannot recognize if Virtuemart cart is empty or not and thus our cache plugin gets automatically disabled when there is any content at your customer's cart. The plugin furthermore supports device type detection in case your template renders different output for mobile devices or desktop devices. Compared to any other page cache solution, our system uses 2 plugins, one which loads the cache on the very first event in Joomla and the other one stores the cache as the very last event in Joomla. It further more supports (if available) advanced functions of latest php versions which can write the cache files after the connection was closed and thus it does not slow down the page load of a non cached page. For this reason the cache is usually available only on 3rd page refresh. The plugin is now distributed within OPC bundle or you can purchase a separate support time with extensions.virtuemart.net or our advanced support link.