Does adding more RAM to your computer make it faster ?

Up to a point, adding RAM (random access memory) will normally cause your computer to
feel faster on certain types of operations. RAM is important because of an operating system
component called the virtual memory manager (VMM).
When you run a program such as a word processor or an Internet browser, the
microprocessor in your computer pulls the executable file off the hard disk and loads it into
RAM. In the case of a big program like Microsoft Word or Excel, the EXE consumes about 5
megabytes. The microprocessor also pulls in a number of shared DLLs (dynamic link
libraries) -- shared pieces of code used by multiple applications. The DLLs might total 20 or
30 megabytes. Then the microprocessor loads in the data files you want to look at, which
might total several megabytes if you are looking at several documents or browsing a page
with a lot of graphics. So a normal application needs between 10 and 30 megabytes of RAM
space to run. On my machine, at any given time I might have the following applications
running:
• A word processor
• A spreadsheet
• A DOS prompt
• An e-mail program
• A drawing program
• Three or four browser windows
• A fax program
• A Telnet session
Besides all of those applications, the operating system itself is taking up a good bit of space.
Those programs together might need 100 to 150 megabytes of RAM, but my computer only
has 64 megabytes of RAM installed.
The extra space is created by the virtual memory manager. The VMM looks at RAM and
finds sections of RAM that are not currently needed. It puts these sections of RAM in a place
called the swap file on the hard disk. For example, even though I have my e-mail program
open, I haven't looked at e-mail in the last 45 minutes. So the VMM moves all of the bytes
making up the e-mail program's EXE, DLLs and data out to the hard disk. That is called
swapping out the program. The next time I click on the e-mail program, the VMM will swap
in all of its bytes from the hard disk, and probably swap something else out in the process.
Because the hard disk is slow relative to RAM, the act of swapping things in and out causes
a noticeable delay.
If you have a very small amount of RAM (say, 16 megabytes), then the VMM is always
swapping things in and out to get anything done. In that case, your computer feels like it is
crawling. As you add more RAM, you get to a point where you only notice the swapping
when you load a new program or change windows. If you were to put 256 megabytes of
RAM in your computer, the VMM would have plenty of room and you would never see it
swapping anything. That is as fast as things get. If you then added more RAM, it would have
no effect.
Some applications (things like Photoshop, many compilers, most film editing and animation
packages) need tons of RAM to do their job. If you run them on a machine with too little


RAM, they swap constantly and run very slowly. You can get a huge speed boost by adding
enough RAM to eliminate the swapping. Programs like these may run 10 to 50 times faster
once they have enough RAM!