When it comes to memory, computers are very much like people. With age, they don't lose memory, it just gets packed with too much content.
You add more files, the system catalogs them. You run more programs, the system actively manages the execution of each one. Newer programs have more settings, perform more functions, and are more graphically intense. All of this eats up memory.
Computers have two kinds of storage: volatile and permanent. For a list of storage devices, see What's a Computer? Here we talk about volatile storage, also known as system memory or RAM (Random Access Memory).
Short term memory
RAM is hardware, "real memory", which the computer uses to store information about the current status of all active processes. Its value is not in retention (the information is lost when programs are closed or when the computer is turned off), or size (averaging 1-6GB), but its blazing speed.
By default, the Windows operating system maintains an extension to real memory in a "page file" on the hard drive. This "virtual memory" is used for storing information which is not currently active and when there is not enough RAM. It helps to prevent the system from crashing due to low memory; but since it involves reading and writing a file on the hard drive, it's ... very ... s.l.o.w.
Get a clue
The textbook case is a computer which is pristine, yet seems to be working hard at being slow:
All system and software updates are current, the hard drives are defragmented and error free, new software has installed cleanly, junk files are minimal, everything is tuned to perfection, there are no viruses, and there are no error messages.
Regardless, the hard drive light shows it is working almost constantly, the CPU is running hard, and the internal fans create a din as they strive to keep the hardware cool.
If you right click a blank space on the Task Bar, click Task Manager in the menu, then click its Performance tab, you can see that the CPU and Page File Usage are high. The Processes tab in Task Manager shows no particluar program devouring system resources.
What's happening is the system is doing little more than swapping information between RAM and the page file, using thousands of slow hard drive reads and writes, trying to provide enough memory for all those hungry programs.
No solution
There are currently several "memory optimizers", for sale or free, which claim to "manage" system memory by manipulating it and/or your running programs in various odd ways. Some of their theories seem rather convincing. Don't use them.
Memory "optimizers" tend to be CPU intensive, making the CPU run even harder; they often use as much or more memory than they recover and make you wait repeatedly while they "optimize" memory; and they can even corrupt the contents of RAM, causing software or system failures.
We saw one of these which severely taxed the CPU and caused frequent interruptions to recover 30MB of memory each time. However, 64MB of memory was permanently recovered by uninstalling the optimizer!
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What to do
First, if you are not comfortable with opening the computer case and tinkering with its insides or researching all of the specifications, then simply tell a computer technician that you need more RAM.
Installing bigger RAM is by far the easiest and most effective solution. In the long run, it's probably cheaper as well since it saves your valuable time. It costs far less than a new computer, and can easily make your computer run like new.
Check the owner's manuals of the computer and its operating system for the largest amount of RAM that is supported by both. Divide this by the number of RAM slots in the computer to determine the size of RAM modules to buy.
Do not install modules of different sizes. Plan to fill all the slots. For example, if you want to install a total of 8GB of RAM, and you have 2 slots, then install a pair of 4GB modules.
Before you buy, look up all of the specifications: maximum memory, number of slots, number of channels, memory type, number of pins, clock speed, latency, delay, precharge, bank interleave, and voltage. You need part of this information to find the right RAM, and part of it to enter into the computer's firmware settings after the RAM is installed. If you can't confirm this information from the manufacturer or retailer, go elsewhere.
The Buffalo and Corsair websites have interactive specification charts to help you find the right product. Corsair is famous for their TwinX modules which are factory matched pairs of identical memory that is screaming fast (because they don't make the computer talk two different languages). Both companies have excellent warranties on their products.
When you change the modules, be just as careful with the old modules as with the new ones until you are certain that the computer works without error.
Configure the page file
The page file is necessary for proper Windows system operation, but its size needs to be set at practical limits based on the total size of physical RAM. If its size varies frequently, the page file can become fragmented and lead to system instability. To begin:
Right click My Computer > Properties > Advanced tab > Performance Settings button > Advanced tab > Virtual Memory Change button
In the list of disk drives, select the drive which has a page file. Normally there should only be one such drive. Typically this is drive "C:". Bear in mind that, when you make changes in this window, you will usually need to restart your system for those changes to take effect.
The simplest way to configure the page file is to click the System managed size radio button, then click the Set and OK buttons. This permits Windows to vary the size of the page file as needed; however this also allows the page file to become fragmented more easily.
While there are different schools of thought about this, the following is a good starting point. Click the Custom size radio button. Type the total amount of physical RAM, in megabytes into the Initial size field (for 1GB, enter 1024). Multiply that amount by a factor from 1.5 up to 2 (for 2GB, use 2048), and type the result into the Maximum size field. Then click the Set and OK buttons.
If you want to shave a few seconds from system startup and shutdown times, get an average of the maximum physical RAM in use during normal operation in the course of several days; then set the "Initial size" to that average in megabytes.
Use the live monitor on the Performance tab of the Task Manager to see if you need to tune the page file size.
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If you have more than one internal physical hard drive, we'll let you in on a Trade Secret. First you need to know that one physical drive can be partitioned into two or more logical drives (partitions), each with its own drive letter.
The page file works best on a primary (usually the first created or only) partition of a physical drive; however it does not have to be on the system drive. In fact, if the page file is elsewhere, the computer can operate both drives almost as quickly as one. Therefore it can read and write data to the page file on another drive simultaneously as it works with the system drive - a significant performance boost.
Find the drive letter of the primary partition of another physical internal hard drive, preferably one which isn't constantly in use and which you know is error free and stable.
Now, in that control panel we told just you about, create the proper sized page file on this other drive letter, then click the Set button, then change the setting for the system drive to No paging file, then click the Set and OK buttons.
If you have the opportunity, you might create on a non-system drive a primary partition of about 2GB larger than the maximum page file size. Then put just the page file and nothing else on that partition. The page file will not fragment.
Note that if you are a programmer who relies on crash dumps, you need to keep the page file on your system drive.
In case you are wondering: don't put more than one page file on the same physical drive - this will actually make your computer run slower.