The diglloydHuge benchmark demands around 56GB of memory during the course of its execution, far exceeding the 16GB memory limitation, but the OS X Mavericks compressed memory feature mitigates the speed hit.
The late 2013 'Crystal Well' MacBook Pro Retina at 2.6 GHz handily outperforms its 2.7 GHz predecessor in Photoshop with an impressive 32% reduction in time required for the diglloydHuge benchmark.
The extremely fast PCIe-based flash drive (SSD) inside the 2013 model is likely responsible for half or so of the speed increase.
Of note was the steadily rising fan noise on the 2012 model during the test, indicating rising temperature inside the machine. It might be that the Turbo Boost feature drops the 2012 model to slower clock speeds.
The 2013 model had only very mild fan noise (just barely audible at close range in q quiet room), suggesting either more power efficient operation or reduced fan noise, or both. The fan noise is considerably lower than with the 2012 model under the same load.