One of the strategic decisions that you need to make when you create your Facebook application is deciding whether to use FBML or an IFrame for your canvas page.
Archive for Application Design Topic
After you have your Facebook application developed, your next step is to see what areas of the app can be optimized to speed up overall performance.
The data-gathering capabilities of FQL are identical to many of the API calls. However, before dismissing FQL as redundant, it is important to recognize that FQL does have some notable advantages over API access to Facebook.