There wasn't much difference with cairo-perf-trace.
For the GtkPerf micro-benchmarks of the GTK tool-kit, the numbers tended to favor Unity 2D, which will not be available within Ubuntu 12.10.
The desktop performance varied based upon the 2D workload, but for a number of the test results, Unity 2D remains much faster than the Compiz-based Unity that will be the only Unity desktop choice available beginning with Ubuntu 12.10. The next set of Ubuntu Unity-focused tests are the power consumption numbers of Unity vs. Unity 2D vs. Unity-Over-LLVMpipe.