Actually a lot more was added, but is still off by default for testing, or the above was prep for items coming in 13 and 14 like auto updates (which you can optionally turn off unlike Chrome) and quicker startup in 14 and tabs on demand and memory reductions in 13. Both browsers are following a 3 month upgrade policy to stay on the cutting edge. It's better than waiting around so that everything on a checklist they want for a particular version is finished.