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How to Disable Superfetch and Prefetch in Windows 8

Posted by Jim Tanous on May 19, 2014
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Prefetch and, since Windows Vista, Superfetch, are technologies in Microsoft Windows that can significantly improve system resposiveness by predicting which applications a user is likely to launch and preemptively loading the necessary data into memory. While essential to ensuring a smooth user experience in systems with traditional hard drives, some systems with solid state drives may not see much benefit thanks to the SSDs’ inherent performance advantage, and Prefetch/Superfetch services may actually be detrimental to SSDs in the long run due to the unnecessary writes they generate.
In Windows 7, Microsoft attempted to address this issue by automatically disabling Superfetch and Prefetch when a fast SSD was detected. In Windows 8, however, the operating system tries to analyze the performance characteristics of the system’s storage and intelligently enable or disable Superfetch/Prefetch as needed.
While most users will be fine letting Windows decide how to use Superfetch and Prefetch on its own, there are situations in which Windows may make the wrong decision, and power users will want to manually disable or enable the services. This most often occurs with non-standard configurations such as fast RAID arrays of HDDs, or mixed use of both SSDs and HDDs.

Manually Disable Superfetch

To manually disable Superfetch in Windows 8, launch the Windows Services manager by right-clicking on the Desktop Start Button, choosing Run, and typing services.msc. Alternatively, you can search for services.msc from the Start Screen.
In the Services Manager, scroll down to find Superfetch, which is controlled by the Windows service called SysMain. Double-click Superfetch to launch its Properties window and click on Stop to stop it.
Disable Superfetch Windows 8
This will kill the service for now, but it will restart automatically at next boot unless we tell it not to. Under the “Startup Type” drop down menu, select Disabled. Click Apply and then OK to save your changes. Close the Services Manager and reboot to have the change take effect.

Manually Disable Prefetch

After you disable Superfetch, you can disable Prefetch from the Windows Registry. Launch the Registry Editor by right-clicking on the Desktop Start Button, choosing Run, and typing regedit. Just as before, you can also launch the Registry Editor by searching for regedit on the Start Screen.
From the Registry Editor, navigate to the following location:

HKEY_LOCAL_MACHINESYSTEMCurrentControlSetControlSession ManagerMemory ManagementPrefetchParameters

Disable Prefetch Windows 8
On the right side of the window, double-click on EnablePrefetcher. You can configure Prefetch in one of four ways by entering the corresponding number in the Value Data box:

0 – Disables Prefetcher
1 – Enables Prefetch for Applications only
2 – Enables Prefetch for Boot files only
3 – Enables Prefetch for Boot and Application files

The default value is 3; setting it to 0 will disable Prefetching.
As mentioned, most users do not need to adjust Prefetch/Superfetch settings, and setting incorrect values can increase boot and application launch times significantly. But advanced users with non-standard drive configurations, or those running Windows in virtual machines, may want to exercise manual control over these important services.

10 thoughts on “How to Disable Superfetch and Prefetch in Windows 8”

Bob Cummings says:
I tried it I set it to 0 and it still saves data, OMG now what do I do? where will I go from here? Oh no!!!
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Howard S says:
What if I have a mixed drive setup i.e. rotating media C: and E: Drive and an SSD D: Drive; What setting should I then use for Superfetch and pre-fetch?
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Kaled Kelevra says:
Good question, i’m in the same position. :/ (but in my case C: is a 120GB SSD and F: is a 2TB HDD)
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Jenda Saba says:
I have problem, that superfetch is still truning on. I did everything what is in the article and after hour and half i chceck my superfetch and its on
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Jaime A.G. says:
I guess this article has got a surge in views during the last month, Windows 10 comes with a memory leak caused by Superfetch and this is the solution! (I helped a lot of people with the problem, probably I linked to this at least 100 times)
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Derek says:
I had some serious lag and freeze issues with my hybrid drive laptop after upgrading from 7 to 10 over the weekend. After disabling prefetch and superfetch (thanks to this article!), I’ve had no other issues.
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Sean Lewis says:
I have a fairly new HP Envy 27 All in One, i7 16GB of RAM Win 8.1, it should have been a radical upgrade from my old Dell Latitude XT but I found that disk was pretty much always at 100% utilisation crippling my experience. I have disabled Superfetch and the disk time has reduced to what I consider normal levels, I’m not sure if Win8.1 is trying to autosense capabilities as per above article but one thing that might be a contributing factor is that the drive technology in my computer is hybrid (both SSD and spinning disk) because the disk controller abstracts this information away from the OS I wonder if Superfetch works against the disk controller causing a bottleneck. Either way, disabling the Superfetch service has worked for me.
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Makiko FlamingSound Honoune says:
I can’t find Superfetch :/
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bigodfw says:
Superfetch started taking up my resources when i switched to ssd i disabled it and now i run way faster.
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John Rayner says:
What are possible negative effects of disabling Superfetch if any exist?
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Sam Houston says:
No ReadyBoost
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Jonilo5 says:
What is ReadyBoost?
Sam Houston says:
You can use superfast thumb drive to create a memory cache that stores the prefetch data into. Reading from the flash drive is much faster than accessing a regular HDD drive.
Jonilo5 says:
Oh, that is nice.
Also, thanks for the explanation! ๐Ÿ˜€
Sam Houston says:
Don’t thank me yet. Many independent researchers have stated this setup, called ‘ReadyBoost’, provides minimal performance enhancements on modern computers. I actually find my year old computer running slower since I installed it.
Jonilo5 says:
Huh, but then could it be good to actually disable it?
If it doesn’t make a moderna computer much better, and not really helping on an old computer, it is useless, right?
Kingjimbo says:
I saw this super old post so I thought why not reply to it :P. Superfetch can cause huge HD usage. So if your HD use is high you might want to try turning it off.
Jonilo5 says:
Ah, thanks for the reply! (actually happy you wrote.)
Sometimes my new computer used alot of HD too, so if that happens again I will do it.
Otherwise I will try to do it on my old computers aswell if I feel it take alot of HD.
Thanks again for the reply! ๐Ÿ˜€
BARON says:
this is nonsense… fetching should not generate unnecessary writes on SSD, it only reads SSD because it is a cache, it only writes to RAM which is faster to access. you should not disable this guys!
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Brian Peterson says:
When I was changing and re-compiling my code and then re-running my executable, my modifications would not show up, the file hash changed and I even moved its location, nothing worked until I disabled superfecth. Disabling it makes enough sense to me.
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BARON says:
right, but you’re a developer and my comment was about an article for SSD users.
Brian Peterson says:
Totally understood, and a typical user or administrator would more than likely dig superfetch, thats not an argument, so, I will agree.
Bo Zhou says:
it drains the battery, generates heat as well so for laptop users with SSDs it’s good for a better experience
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JonasTone says:
I had to disable this because for no reason, it spools up while i am playing fullscreen games, such as black ops 3, and in doing so it uses 16-20% CPU and makes my game (also running from my SSD like windows) drop frames and lag terribly. I want to disable it because it makes problems for me.
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