Published yesterday on Phoronix were the Ubuntu's Unity/Compiz Gets Even Slower and Intel SNA Ivy Bridge - September 2012 articles.
The Unity/Compiz performance is getting slower with the newer packages while separately the other article looked at the Intel SNA acceleration architecture, which happened to be running from an Ubuntu system with the Unity desktop.
Chris Wilson, the Intel OTC developer responsible for spearheading SNA's development, subsequently wrote in the forums: " These set of benchmarks still have some bogosity behind them. There should be no difference in the copy throughput since that is GPU bound using identical operations, but most of the rest can be explained with the choice of unity wm and using ubuntu. Comparing results from a mobile GT2 device (a i7-3720qm) with this article a deskop GT1 chipset we get the impression that the system under test underperformed significantly."
Chris Wilson ran some additional 2D benchmarks that matched the Phoronix tests to show what he gets when running UXA and SNA bare without Unity (he's using Debian) and when relying upon the GNOME Shell. Those interested in his results without Unity to show the 2D performance improvement, see his OpenBenchmarking.org result file. You can also join the fun yourself by running these benchmarks through running phoronix-test-suite benchmark 1209044-SU-1209034SU66 after having installed the Phoronix Test Suite software.
Wilson's data also jives with an earlier Phoronix article looking at the 2D performance under Unity/Compiz: Ubuntu's Unity Decision Affects 2D Performance Too. Fortunately, new cross-desktop OpenGL and 2D benchmarks are on the way.
Also, for those wondering about the performance regression caused by the latest Unity/Compiz, Sam Spilsbury working for Canonical on Compiz, wrote an explanation in the forums for the regression.