XP: Registry Hack to Disable or Modify Prefetch

You can change the amount of memory stolen by prefetch or stop it completely using this tech-recipes tutorial.


Prefetch does exactly what its name implies: it loads programs, libraries and everything else the computer deems often (at one time) and loads them all into memory, whether or not they are commonly used now and even if they do not exist now. These programs and files could still be using some of your memory, so get it back.

This option does speed up the opening and running of popular programs, but it should also be kept under control.

Clean Up the Prefetch Folder:
Navigate to C:\Windows\prefetch.
-Delete any heading which you do not use often enough or if the program loads quickly without being prefetched.
*NOTE: You can delete them all, if you like. They will be updated again when Windows deems fit.

The items removed will likely load a little slower than usual the first time you run them, but this is a reasonable trade off if your overall system performance is improved.

Determine How You Want Prefetch to Run:
*This involves the registry. If you are uncomfortable with editing the registry, you should stop here.

Move to path: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management\PrefetchParameters.
On the right side, look for a key named EnablePrefetcher.
This decides if and how prefetch runs. Here are the values and what they do:
0: Disable
1: Prefetch when an application runs
2: Prefetch on startup or bootup
3: Always Prefetch

*Here you will have to make your own decision on what is best for your system. I personally do a boot on app run. The wait time is very minimal compared to any other setting, and Windows startup is considerably faster, which is what really matters.
Once a program has been added to prefetch, it then will run faster the next time you open it until reboot.

Further information regarding the prefetch can be found here:
XP: Speed Up Your System – When, Where, and How to Clear the Prefetch

Questions/Comments: [email protected]
-William. ยง (marvin_gohan)

The Conversation

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  • Mitu

    Mucho thanks Larry…. I really appreciate it…

  • ClearlbyBiased

    I have prefect running with the scheduler. Every few days, or so, I delete the contents. Always makes things load faster. Almost instantly when I delete the fetch. Then wait and wait after a few days of a full fetch.
    Why? Others have the same thing. I was hoping to find that I could list only the 15 or so programs I use most often. Like setting the “page” to 15 instead of 4000 (dec) but that probably isn’t the right approach. I need to find someone who understands the interplay of the parameters. I also know it degrades when I use the registry to turn it off.

  • Anonymous

    I do not like prefetch system. I believe to be another Microsoft BS. When I delete my prefetch directory my PC starts faster and without any problem.

    Once a virus kept reappearing, it was loaded in a prefetch file.

    Based on this experience, I have modified my shutdown and reboot system –> they empty the prefetch directory.

    I am having less problem since.

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