As a number one open source eCommerce platform with several years of development behind it, I'm sure you'll agree that Magento is one of the most complex pieces of PHP software ever created. Logical consequence of complexity Magento brings to the table is relatively low performance when compared to custom made eCommerce solutions. In order to improve this situation, Magento stacked several layers of caching one on top of another, with full page cache being the topmost layer, and one that's exclusive to Magento Enterprise Edition. Having power of full page cache nearby is great, but I must point out that by creating custom controller action in Magento you don't automatically benefit from performance boost FPC offers. In this article I'll outline how Magento Enterprise Edition full page cache works, and what you need to do in order to take advantage of features it provides at your custom controller action.