I believe, this feature is the major & most important need of JSF for high performance applications. When not required, it is simply a waste to save state redundantly when there is no difference across the views saved for a page in different user sessions. For most developers looking for a high performance framework, JSF is turn downed because of its forced stateful behaviour. However in any application not all pages need to be stateful, even more commonly there are more no of applications with pages demanding stateless behavior. If JSF has to survive & excel it has to satisfy those justified needs.
Unfortunately, we had to reject JSF, after year after just because it consumed too much resources & degraded its performance because of its forced stateful behavior. Great to see that this feature is being worked on in JSF & but I wish that we can see this in JSF soon rather than hanging ourselves with forced stateful behaviour for another couple of years. Can't wait to use stateless JSF for my upcoming projects!