One of Microsoft's big selling points for Windows XP was that it loads applications much faster than its predecessors. To accomplish this feat, Windows XP uses what is called the "Prefetch technique," in which the operating system gathers information about each program that you launch and stores that information in the \Windows\Prefetch folder. Then on subsequent restarts, Windows XP uses the information in the Prefetch folder to essentially preload parts of those programs at boot time. Thus, when you launch your application, it appears to load really fast.

However, the Prefetch folder can accumulate too much information over time. This makes the operating system so busy loading bits and pieces of lots of applications into memory that it ends up slowing down the boot process. Fortunately, you can clean out the Prefetch folder at any time. Follow these four steps:

Access the Run dialog box by pressing [Windows]R.
Type Prefetch in the Open text box and click OK.
Press [Ctrl]A to select all the files.
Press [Delete].

As you use your system, Windows XP will rebuild the contents of the Prefetch folder.