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Tech Tips / Windows XP / Performance Monitoring and Optimization

Run optimizations manually

Windows XP actively monitors every application startup and logs the files that are used. The same logging is enabled when the operating system loads. Memory pages are logged in the
%windir%\prefetch folder. In fact, each application you run will have a special file in this folder.

When an application is launched, XP looks at the corresponding file in the prefetch folder and loads the required data. By knowing what data the application needs, the OS can consolidate disk seeks optimally and reduce head movement. Thus, it improves the overall performance of the OS and applications.

Periodically, XP parses the files in the prefetch folder and creates a Layout.ini file. This file includes the information about the optimal layout of files on your hard drive. The built-in defragmenter uses this information to optimally defragment the hard drive every three days.

While you normally don't have control over this automatic procedure, it's possible to accidentally disable some of the optimizations. For example, if you disable the Scheduler service, you also disable the automatic defragmentation. XP schedules the defragmenter through the Scheduler service but doesn't show it through the user interface.

Fortunately, if you do disable the Scheduler service, you can still manually run the optimizations. Just open the Start menu, select Run, and type the following command:

rundll32.exe advapi32.dll,ProcessIdleTasks

This command will run all the tasks XP runs when the computer is idle.

To see how the computer performs without prefetching, turn off this feature. Here's how:

1. Open the Registry Editor (Regedit.exe).
2. Go to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\
   Session Manager\Memory Management\PrefetchParameters\.
3. Set the EnablePrefetcher to 0.
4. Delete the layout.ini file from the %windir%\prefetch folder.

Since the system runs faster with Prefetcher turned on, you typically will not want it disabled.

Note: Editing the registry is risky, so be sure you have a verified backup before saving any changes.