Why You Should Not Disable SuperFetch in Windows 7

What is SuperFetch ?

SuperFetch is one of the reason that makes you feel Windows 7 runs faster and smoother then any of it’s predecessor, although it has been out since Windows Vista Microsoft has yet made more performance tune with this service. SuperFetch is basically a service that runs actively in the background to cache up the most frequent used application into the memory. What is going to be cached are the programs and data files you as a user will most frequently use based on your prior usage. It will observe your PC usage pattern and from that predict what you will most likely to use. It’s also one of the reason why you see Windows Vista uses much more memory than Windows XP, since the concept is to retrieve data from the faster RAM rather than the HDD, slowest I/O device. This is also the reason behind why sometimes you can hear your hard drive glitching but you are doing nothing. This is because SuperFetch is caching the data, though it is always run in the minimal priority.

superfetch

What Would Happen If I Disable it ?

So by disabling the SuperFetch will defiantly increase the available memory (more free memory as in memory holding no data what so ever), but by doing so you will get horrible performance. Not only the boot time of your system will be longer, application launch time will be longer as well. In the end, you might thought you are getting additional free memory from this trick but you will not be benefiting from any of this. It doesn’t matter if you have large memory or small memory, leave it on and let the Windows manage memory and I/O usage is the best way to increase the performance and stay fast.

In the end don’t get trick that you see more memory are free from the task manager, the free memory is doing nothing whereas before the free memory will cache your application and data file for faster process to the CPU. The disk is the bottleneck for all system, and SuperFetch is designed to minimize the bottleneck for the overall performance.

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  4. How To Remotely Enable/Disable Remote Desktop Connection on Windows 7 and Windows 8
  5. Hiberfil.sys in Windows 8 and Why You Should Never Disable Hibernation To Delete It
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  • Anon

    I disabled SuperFetch, Prefetch, ReadyBoost, Indexing, etc. in Vista because they were trashin my harddrive, even with a highly specced Dell laptop (worst purchase ever, but you learn not to buy Dell…)

    I make it a point to do it in Windows 7 also. I’m not afraid of “decreasing performance”. Especially with my new SSD disk, things should be pretty fast without SuperFetch.

    What I don’t like is default services which unnecessarily slows down the system and requires memory to run, and even writes to disk over and over again. Maybe these services have been fixed, so that the trashing doesn’t occur and they can run when the system is not in use. However, from my experience, these services are writing by brute-force, and can seriously degrade a poor SSD disk.

    Windows 7 is an improvement, but these services, and a pagefile which the OS decides to write to even though I have more than enough free memory, is annoying still. I have yet to see as good performance from default settings, compared to when unnecessary features are turned off.

    PS. Boot time is not important to me, but with SSD these services (possibly except pagefile) are becoming more and more irrelevant, which was my gut feeling from the start.

    • http://www.windows7hacker.com Kent

      Good point. Actually, Windows 7 is designed to be optimized automatically with SSD. It’s smart enough knowing to disable defragment, superfetch, readyboost, etc. automatically when a ssd is detected in the system. Windows 7 is the first OS in windows that is optimized with the new SSD.

      Cheers.

  • gggirlgeek

    I don’t know about this. I have Win7 running on a system with 1 Gb Ram and two large SATA drives — 1.6ghz duo. The only problems I’m having are the write speeds to the hard disk — even when just moving to the recycle bin, which is not really moving, it’s renaming, it moves as slow as a network transfer. I have tried a bunch of things to speed it up and now have Super Fetch turned off. I am not seeing any slow down, or speed up at all. I’ve had it turned off for more than 3 months. However, the annoying, and paranoia provoking, disk writing in the background is indeed gone. That is very nice!

    In fact the only time I need to restart my system is after a full night of high speed downloads — aka disk writing. The only time I have trouble running programs is when Media Center is recording a TV show in the background (again disk writing.) The only programs that give me trouble in the background are disk intensive Evernote and Mediamonkey.

    My average transfer rate between folders ON THE SAME PARTITION is 12MBps. These should be simple directory renames but I can hear it moving the data — with 100Gb free this should not be needed.

    Something is up with the way Win7 handles disk writing.

  • Amin

    I have a Question:
    You said: “What Would Happen If I Disable it? … Not only the boot time of your system will be longer,…”

    If caching is happening in the RAM, (instead of the slow HDD) at booting time, RAM is empty. As far as I know, RAM will be emptied every time you restart your PC. So how can Catching in RAM help reduce Boot time?

  • James

    One nasty thing I noticed with Superfetch from Vista is how it works with Bitorrent. When Bittorrent is on, Superfetch is constantly trying to cache the huge file your are downloading (it’s a frequently accessed file right?). As a result, your computer slows and your hard drive looks like it’s about to die from exhaustion. I don’t know whether this has been addressed/fixed but it’s one of the reasons why I’ve turned Superfetch off.

  • Bughunter

    this is a bad feature – if you think about it, how many applications and files are you using if you are actually working with your pc? Do you need to spend lots of memory just for the case you might want to startup another application and save 5 seconds on this – but loose lots of ram for other apps?
    As always, windows developers tried to copy ideas from other systems, but failed to implement them in a sane way – ending up with a bloated system that needs even more ressources – this is a big problem for the whole planet, as we can not afford operatig systems that are eating actually more ressources than before, it should be the other way around! For the sceptics: yes, our ressources are limited on this planet, this is a fact – that means all systems have to go to low ressource usage, not stupid ressource usage.

    • Pat

      Couldnt’ agree more! How many nuclear plants, or CO2 spewing plants, are we going to dedicate to running Flash ads and other crap?

  • jesus

    i have i5 2500K overclocked to 4.5GHz, SATA hdd. I disabled superfetch, I feel almost no difference in boot time or application load time. However, latency has been improved, hence, application that requires low latency performs better, like gaming, foobar, asio etc

  • IT support

    another article claiming that disabling superfetch will “slow down” your computer. In fact, for most computers out there, superfetch presents problems by eating up precious HDD read and write bandwidth, something that causes the computer to slow to a crawl (since it’s the only bottleneck anyway) On 100% of the computers i’ve worked on, disabling superfetch sped up the system, consumed less power (laptops) and caused the computer to become quieter too!

    • http://about.me/kentchen Kent Chen

      Sorry, I don’t agree. Unless you are using SSD, you should not disable superfetch or prefetch.

      • Dr. Harri

        Why is that? In your opinion, if my computer is practically unusable with Superfetch undisabled, should I rather use a typewriter? Or what would you suggest?

        • http://about.me/kentchen Kent Chen

          Well, there could be other issues in your computer that makes it unstable. While disabling it seems to be better in your case, it certainly didn’t fix the problem that is already in your system.

  • Pat

    So Superfetch magically makes work disappear?
    In fact, it seems to always do it’s “magic” at the wrong time, and bog the system down.
    I’d MUCH rather wait an extra second for an app to launch than have my system bog down for no apparent reason at the wrong time. MS have basically got this one fundamentally wrong. Second guessing and bringing in wast amounts of things that may never been used will likely push out things that are being used -at least the effect it seems to have on my oh so underpowered 4 core 8GB RAM machine.

  • Dr. Harri

    My dear Jonathan Hu, what you write is what I would call fucking bullshit. Superfetch fails to predict my usage patterns for the logical reason that they are unpredictable. When it is on, it every now and then consumes 100% of my HD bandwidth for several minutes so that I get no response from the machine at all. In this situation a faster launch time for some application is quite theoretical (I generally have time to wait for 30 seconds but usually not for five minutes). Surely I can boot another computer in the hope that it would work better (I have two laptops and a desktop usually at hand), but I don’t think that this is very effective. So, it is better to just discard the Superfetch nuisance.