This quick entry announces that we've started work on JSF 2.1 in earnest.
Soon after Oracle acquired Sun, Blake Sullivan and Andy Schwartz, Oracle UI Technologies Architectects from the ADF Faces team, donated a significant patch of performance enhancement work to the Mojarra project. This work initially went into JSF 1.2 and will be in the upcoming Mojarra 1.2_15 release. I have recently completed integrating it into the HEAD branch of Mojarra for JSF 2.1. The easiest way to try it out is to grab a GlassFish 3.1 nightly build from 14 July or later.
If you're interested in the specific fixes, this java.net query shows them up.