During a media event at GDC 2013 Intel announced that the new version of the IGP driver might bring pefromance improvements of up to 10 percent for the HD 4000 IGP.
The driver was originally developed for the upcoming Haswell processors but should also bring performance improvements, bug and stability fixes as well support for OpenCL 1.2 for Ivy Bridge owners as well. The performance improvement apparently comes as a result of better balancing load between GPU and CPU and should also lower power consumption.
It is still not clear if the new driver and its performance improvement have an effect on all Ivy Bridge CPUs or just the HD 4000 IGP. Intel is also working on a new driver for Sandy Bridge CPUs and their HD 3000 IGP.
The version 15.31 should be available for Ivy Bridge based system sometimes this week.