Oh I didn't know there was that variable. So was my instinct right? It should be faster?
It should be faster, especially in daily use outside of photo/video editing/processing and gaming. Email, Web browsing, Office/iWork, Media playback should all be a better user experience than your current machine. Especially with that screen.
For reference, I have an 11" MBA with the Maxed BTO Sandy Bridge (2nd Gen "tock", 32nm process, 17W TDP) 1.8 GHz (2.9 GHz turbo boost) dual core i7, 4GB 1333MHz DDR3 RAM, 256GB non-PCIe SSD. Intel graphics 3000 (up to 130 GFLOPS*).
The new maxed BTO rMB will have the Broadwell (4th Gen "tick", 14nm process, 4.5W TDP) 1.3 GHz (2.9 GHz turbo boost) core M, 8GB 1600MHz LPDDR3 RAM, 512GB next gen super fast PCIe SSD. Intel graphics 5300 (up to 346 GFLOPS*).
I expect that these two machines will have similar benchmarks on synthetic tests like Geekbench, etc. However, I also expect that the MB will feel and behave faster and smoother in real life user experience in the categories I mentioned above.
Not to mention, you will be getting the latest tech, like USB 3.1 (gen 1) with up to 10 times the bandwidth and data transfer speeds of your current USB 2.0 ports. Also 802.11ac Wifi as opposed to 802.11n in your 2011. Battery life to die for (compared to the 2011 models). Force Touch trackpad.
That said, this won't be a heavy lifter, if that is what you are in need of. Perfect office productivity machine, though, in my view, and that's exactly what I plan on using it for.
Edit: tick and tock as in tick-tock upgrades Intel is known for. Sandy Bridge was a new architecture (tock) while Broadwell is a die shrink of Haswell (tick). So 2 generations of architecture seperate the two.
*
By comparison, the GPU in the iPad Air 2 can do around 300 GFLOPS. The rMB and iPad Air 2 are pushing roughly the same number of pixels. I don't foresee retina being any problem at all for the rMB.