More detail I�m not aware of any performance studies that have been done yet on JSF and made public. I follow this space very closely and keep an extensive set of resources for JavaServerFaces on my website at:
Yu, I don't think the layer of rendering would be significant compared to the time it would take to get data from a database.
I'm more concerned with the number of server round trips. It seems like more is done on the server resulting in more form submissions. Note that I haven't used JSF in a real application yet, only read about it.
I think JSF is going to perform as well as the other web frameworks. I think one of the watchouts with JSF is that is extremely powerful and very events driven. Since we are dealing with a stateless protocol each event invoked causes a call back to the server. This means without really understanding JSF it can be very easy to build chatty applications.
John Carnell<br />Principal Architect<br /> <br />Netchange, LLC<br />1161 HillCrest Heights<br />Green Bay, WI 54313<br /> <br />firstname.lastname@example.org<br /> <br /> <br />Author of <a href="http://www.amazon.com/exec/obidos/ASIN/159059228X/ref=jranch-20" target="_blank" rel="nofollow">Pro Jakarta Struts, Second Edition</a>