I am using JSF 2.0 and I am looking for a copmponent library with minimal load in terms of performance. Which one is better to use if I have choice between RichFaces and PrimeFaces? What are the advantages and disadvantages of both?
Currently Primefaces is the only component lib that I know of (for now) that has a complete JSF2 implementation. There are bugs and problems, and some components are to be rewritten, but development is lightning fast, the communication is excellent (I don't remember a single post on their support forum that hasn't been answered by Cagatay himself), and it is moving in the right direction (the new theming system is an example of that IMHO). I think Primefaces will be a mature JSF2 component lib by the end of the year.
There are some others, like Icefaces that I played with for a short time, but they are moving slowly and like I said, none of them are really JSF2 yet. Part of the reason for this is that Mojarra, the Sun reference implementation is quite buggy, and there some serious bugs that these component lib developers are waiting for to get fixed.
So my vote is definitely on Primefaces for now, we'll see how it will look like later.