Haswell-targeted release brings better performance. http://www.bit-tech.net/news/hardware/2013/04/02/intel-hd4000-boost/1
Intel seriously needs to up the game on drivers development. It is good now they are releasing drivers update. Unlike a few years back where they could care less. But they should either have smaller update that are released more frequently or having an update every quarter with more bug fix and improvements.
Unless I missed something they are releasing roughly one per quarter +/- a month or so. They also seem to be packing a fair number of improvements that at least some users would care about in each release along with a fair number of bug fixes in there too. Compared to how Intel previously operated, they have stepped up their game big time. A ways to go, but a major sea change compared to before.