16gb of RAM with an SSD? What are you doing on that thing??
Admittedly I do push my laptops harder than most...
Various virtual machines running simultaneously
Various pieces of Adobe software
All sorts really....
But occasionally, Firefox just feels like being a memory hog and going back to its old ways of using up 2 or 3GB of RAM for no perceptible reason at all.
But yes, it did occur to me when writing my previous post, that for the average Joe, perhaps SSD based swap space would not be the end of the world. But I've never tried it so I can't condone it, hence my (perhaps) "old school" suggestion of just boosting RAM.
On the subject of soldered RAM, there is also this quote from an ASIC design engineer (my highlighting of the last paragraph) :
You seemed to wonder why the memory on the MBP Retina would be so much faster than the memory on the regular MBP or any other machine. You were correct when stating the memory soldered on would be more efficient. When designing a motherboard the manufacturer must adhere to a defined standard for the DIMM that is selected. This includes wire lengths, and capacitance, and results in generally slightly less than ideal settings to make it compatible with a vast array of different manufacturers. By soldering the memory directly on to the board Apple is able to define the exact memory access scheme, as they will only ever have to work with the chips that they selected, and don’t have to meet any standards for the DIMM connectors, etc.
This allows the fine tuning of latency to the absurd levels. In fact, with the 22nm Intel there is an option via low level register programming, to reduce the latency of the DDR memory down to 0 clocks. While this is not possible in reality, it gives Apple the room it needs to fine tune the memory and provide the best throughput possible. The values you were reporting were almost 100% utilization of the FSB of the CPU (16,384 MB/s being 100%). You were reporting 99.90% utilization, which is UNHEARD of, but not impossible.
If nothing else, you must tip your hat to Apple for this, that is an incredible job of matching memory to memory controller, and setting the CPU to properly utilize the memory. You will NEVER see this on a computer that supports DIMMs, it is not possible.
(Those words from this website
MPG - Apple MacBook Pro Retina Quad-Core (June 2012) - 2012 MBP Retina ? Memory Bandwidth)