Memory upgrades


Memory

The easiest way to increase the working performance of your Mac
Apple has traditionally been a bit stingy with the amount of RAM it includes with its systems, so Macs often run out of RAM breathing room as users begin to make more sophisticated demands on their systems. Of all the hardware improvements you can make to your Mac to dramatically improve performance, adding RAM is usually one of the least expensive and most effective.
Adding more RAM makes it possible to have more applications and documents open simultaneously without making the Mac have to swap what's in its RAM to a virtual memory file. Using virtual memory is much slower than using 'real' memory, because it's actually a file written to the hard drive.
The first thing you'll need to do is figure out how much RAM is currently in your Mac. If you're not sure, select About This Mac from the Apple menu, and it will tell you. In Mountain Lion, clicking the More Info button yields an overview of how your Mac is set up; clicking the Memory tab will tell you specifically how your Mac's memory is configured to work.

Soldered on

Some Macs don't have upgradable memory, like the MacBook Air, the new 21.5-inch iMac and Retina display-equipped MacBooks; the memory is soldered onto the motherboard and can't be easily replaced. Others, like the Mac Pro, new 27-inch iMac and recent-era Mac minis, can easily accommodate additional memory by replacing existing chips or using existing open slots.
The More Info window can be deceiving: it might tell you your MacBook Pro has two memory slots, each of which accepts a 1600MHz DDR3 memory module and each of which is occupied by an 8GB memory chip. That's how it appears to the system, but if it's a Retina display-equipped MacBook Pro, it can't be upgraded.
Third-party vendors such as Crucial offer easy-to-use web-based tools to help you figure out which RAM to order for your particular system, or even if your particular machine is upgradable at all.
For what it's worth, Apple is okay with users opening up their machines to put in more RAM. Some Macs are more accessible than others - older Mac minis, for example, require a spudger tool to pry the case apart and demand extensive disassembly before you can get to the RAM; newer ones make RAM slots available by turning a panel on the bottom, no tools required.
If you decide you're up for doing the job yourself, make sure to take precautions: work in a clean, well-lit area, and keep an anti-static strap on your wrist to keep the chances of zapping your Mac's delicate circuitry to a minimum.

Solid-state storage


SSDs

Replace your aging hard drive with the latest solid-state technology
Solid-state drive technology (SSD) is being used more and more in new and old computers alike, and it's easy to see why. Apple's been able to produce ever-more slender laptops in part by eliminating bulky hard disk drives and replacing them with much faster solid-state storage.
A hard disk drive is a very physical device. Under the hood of a hard drive is a magnetised platter, or sometimes a stack of platters, rotating around a spindle at a high rate of speed - typically 5400 or 7200 revolutions per minute. A small actuator arm extends from one corner of the enclosure to just above the disc surface, where tiny heads read from and write to the surface of the platters magnetically.
If it sounds archaic, that's because it is. Hard drive technology has been around since the 1950s. By comparison, SSDs have no moving parts. SSDs are simply integrated circuits that store data even when the power to the computer is turned off, thanks to the use of a special type of flash memory (similar to what's used in iPads and iPhones).
Because there are no moving parts, SSDs are much, much faster than hard drives: reading and writing data is quicker, and you spend less time waiting for the 'disk' to find the information, too. They're also less susceptible to physical shock for the same reason, and they produce no noise.

Not cheap

If SSDs are so great, why isn't everyone using them? They're still relatively expensive - many times more expensive, per gigabyte, than a hard disk drive, at any rate. Consider that a 128GB SSD can cost the same as a 1 terabyte (TB) hard disk drive. So unless you have very deep pockets or a very generous benefactor, chances are you're going to pay a lot more for a lot less storage.
But what you lack in storage you will make up for in blazing speed. While boosting RAM may offer the best overall bang for your buck, replacing a pokey old hard drive with an SSD is the quickest way to supercharge an ailing system, especially since paging RAM out is much faster.
SSDs now come available in replacement enclosures that look like traditional hard disk drives, and they will drop right into place where the hard drive goes - the screws to hold them in place will line up right where you expect, and the cabling is the same.
If the idea of less storage is daunting, there may be another solution. Other World Computing, for example, makes kits that enable some MacBook and MacBook Pro users to remove the SuperDrive and fit the hard disk drive there instead, then put an SSD in the empty spot where the hard drive was.
Or, if you're using a Mac Pro, you can put an SSD in an empty SATA hard drive bay. In those cases, you can move your OS and crucial apps and documents to the SSD but continue to use a hard disk for long-term storage. 
Expansion slots

Slots on your Mac can offer various types of expandability
The Mac Pro is the most expandable of any Mac model, and while not available for sale anymore in Europe as of March 2013, plenty are still in use in professional settings because of the system's massive horsepower and extraordinary flexibility - it's Apple's heaviest iron.
The Mac Pro can accommodate four PCI Express expansion cards (one is already occupied by a video card). PCI Express is a widely adopted standard in the PC world, so many manufacturers make cards, but only some offer Mac-specific cards or Mac drivers to enable them to operate.
Cards available for the Mac Pro include exotic high-speed networking technology like Fibre Channel, or external SATA (eSATA) - a faster hard disk interface than FireWire. Professional digital video companies manufacture specialty cards to enable the Mac Pro to input and output broadcast and cinema-quality video, which can take up massive bandwidth. There are also USB 3.0 cards; while it's become standard issue on other Macs, USB 2.0 is all that the Mac Pro includes from the factory.
Some Mac Pro owners have maxed out the number of internal drives their systems can handle (there are four bays, each capable of supporting a 3.5-inch drive). For those users, adding additional SATA expansion cards can be handy, especially if it's time to start incorporating SSDs in the mix. Put in an array of SSDs and you can set them up as a RAID for even faster performance.
The now-defunct 17-inch MacBook Pro, which went out of active circulation in June of 2012, was the last MacBook Pro to feature an ExpressCard/34 slot - an expansion slot that offered PCI expansion capabilities. Cards available for the MacBook Pro include FireWire 400 and 800, eSATA, USB 3.0, additional Gigabit Ethernet ports and more.

How fast can a Mac go?

Replacing hard drives with SSDs, adding memory and fine-tuning the software contents of your system are all fine ways to improve the performance of your current Mac, but how fast will the Mac get?
From processor improvements to bus speed changes, different types of data storage and more, let's take a look down the road.
Let's start with Wi-Fi. All of Apple's currently shipping products use 802.11n technology, which can transfer data - in theory - at up to 300 megabits per second (Mb/s). Routers are already hitting the market that support the fifth generation Wi-Fi spec, called 802.11ac. 802.11ac can transfer data at up to 1 gigabit per second, and the industry anticipates widespread adoption by 2014. (The routers available today are only using a preliminary version of the 802.11ac spec, and no Macs support it natively yet; tread carefully.)
There may be a reason to postpone your purchase of any 802.11ac networking gear, at least for a bit. Another wireless networking technology called 802.11ad is coming in fast behind 802.11ac. It'll work at up to 7Gb/s, with backwards compatibility for older, slower systems.
Of course, not everything can be wireless - sometimes you still need a good old fashioned cable to connect peripherals to your Mac. To that end, the current state of the art is USB3, which can transfer data at up to 5 gigabits per second. At CES earlier this year, the USB Promoter Group announced a new USB3 enhancement that doubles USB3 to 10 Gb/s instead. That puts USB3 on a similar level as the transfer speed of a single lane of Thunderbolt (Thunderbolt actually uses two lanes, with effective bandwidth of 20Gb/s).
Thunderbolt isn't sitting still, either. It's due for an overhaul late this year, when Intel introduces new silicon that will double the effective bandwidth of Thunderbolt from 10 gigabits per second, per lane, to 20Gb/s per lane. Chips featuring the new 'Falcon Ridge' controller are expected to be widely available in 2014. And Intel says there's plenty of room left to grow Thunderbolt even further.
Serial ATA (SATA) is the interface Macs use as the hard drive or SSD interconnect. In its current form, SATA 3.0, the interface can transfer data at up to 6Gb/s second. SATA was designed at a time that mechanical hard disks were still state of the art, however, and times have changed. Some higher-performance SSDs are already hitting the limit of SATA 3.0 interface, maxing out that 6Gb/s speed limit.
But relief is in the works, according to the Serial ATA International Organization. SATA Express, officially announced at the CES trade show in Las Vegas, Nevada earlier this year, is a recently proposed spec that will up the speed limit even more. The organisation says that SATA Express will be able to move at up to 16Gb/s.
SSDs aren't the be-all end-all of storage technology, either. Already a company called Everspin is selling 'Spin-Torque Magnetoresistive Random Access Memory' or ST-RAM, a non-volatile solid state storage medium that it says is 500 times faster than current SSDs. The downside, predictably, is price - currently ST-RAM costs about 50 times more than SSD, and SSD is no value compared to a cheap, old-fashioned hard disk drive.

Further ahead

Looking much further down the road, researchers are working on holographic data storage. This optical storage medium stores data in three dimensions instead of two, such as on a DVD or Blu-ray disc, which increases the storage density of the material dramatically.
Genetics researchers have also tested the viability of using DNA as a storage medium, though they admit they're decades away from having real working storage systems available. And IBM is working on storage systems that record data at the atomic level.
Macs will, predictably, add horsepower through improved processors. The next jump in Intel hardware is making its way into the world now with the introduction of Haswell microprocessors, which replace the Ivy Bridge processors used throughout Apple's Macintosh product line today.
Intel's longer-term roadmap calls for continued refinements in processor architecture and a reduction in die size, allowing for ever more complicated processors that gradually grow more power-efficient. While Intel hasn't outlined all of its plans, we can count on chips with even more cores capable of multiprocessing capabilities well beyond what the CPUs in Apple's machines do today.
Ultimately, Haswell will be supplanted by Broadwell, Skylake and Skymont processors through 2017. Intel CEO Paul Otellini believes that silicon, the material that serves as the base of all current CPU designs, is probably in its last decade of use.
Intel hasn't said what it will replace silicon with, but if IBM's research is any indication, carbon may be a safe bet. IBM researchers have built circuits out of graphene, a highly conductive one-atom thick sheet of carbon molecules. It's possible to build much smaller, more powerful chips using graphene.

Quantum computing

Gazing further into the future still, physicists have hypothesized about the feasibility of the quantum computer - a computer that stores data using quantum bits, or 'qubits,' instead of the regular binary bits (0s and 1s) that comprise today's machines. Qubits make it possible for quantum computers to work potentially millions of times faster than today's machines.
Quantum computers aren't a pipe dream. In fact, they've been produced in laboratories since the late 1990s. And one company, D-Wave actually makes what it says is a commercially available quantum computer, a 128 qubit system priced at US$10,000,000.
Clearly, some of this stuff is years away from finding its way into the Mac. But a lot of this technology is just a matter of time. What's for sure is that Apple will keep Macs performing as fast as possible, as soon as it reasonably can. We can't wait!