Many Vista users (or people who have never used Vista) complain that the operating system uses too much RAM. They look at the performance monitor and see there is a lot less available RAM – when compared to Windows XP. The extra use of RAM in Vista is partly due to a performance enhancement called SuperFetch. Having low free memory in Vista shows this is working.
Please note: I wrote a guide on disabling Superfetch. In this guide I tell you to let Superfetch run. My advice is to disable Superfetch if you have less than 2GB of RAM (this is a generalized number as all systems are different.) If you have more than 2GB of RAM, Superfetch will work to your advantage.
Comparing XP and Vista RAM Usage
The following two images show performance on an XP and a Vista machine (both 2GB RAM) running under normal circumstances. Notice how there is lots more free RAM in XP (XP also preallocates RAM, but nothing like Vista does). Also note: XP displays RAM in KB and Vista displays it in MB.
XP treats RAM as a resource to be used only when needed while Vista treats RAM as a cache and uses almost all of it as soon as it becomes available.
What Does Superfetch Do?
Superfetch works out what applications you use most often and builds a database of your work patterns. This information is then sent to the disk defragmenter to ensure those applications are stored optimally on your hard drive. This information is also used to preload the most commonly used applications as you log on to Windows. Finally, Superfetch takes care of I/O on your system and prioritizes your most important applications; inputs and outputs from vital applications take precedence while you are using them.
Yes, you guessed it — a combination of the three actions above speed up the process of opening a program. Hopefully this guide was helpful by letting you know what Vista is up to when it’s using so much RAM all the time.