So this question came up today and I didn't have a specific or scientific answer.
What are the costs associated with using jsf (or tomahawk, faclets, etc., etc.) tags in place of traditional html tags. My gut reaction is that you should use jsf tags in situations where you need the additional functionality they provide, and use traditional tags when you don't. Also I feel like jsf tags would require more resources (since the server has to take them and rerender them as html anyways) than html. Does anybody know what the cost actually is (as far as time and memory)? Also useful information is what is the convention that is in use, pure jsf or a mixture of the two?
Our site http://www.skill-guru.com runs on JSF/ Tomahawk / Rich faces on a tomcat server. We do not see any speed issues here. As Jeff pointed out , it all gets compiled so there is not much noticeable difference until and unless you really use too much rich faces or other fancy stuff. JSF does help you make your life easy.