Just Say No To SuperFetch


Fetch, boy!

If you’re using Windows Vista, then you’ve probably noticed the new memory requirements.  In Windows XP you could get away with 1GB of memory, with 2GB making it run much smoother.  To get the same smooth  experience from Vista, you really need to double the memory, due in part to some of the new services that Vista is running.

One of these new services is SuperFetch, which analyzes your program usage and pre-caches these programs to make them load faster.  For most users (especially gamers) this is relatively useless, and just serves to waste more of the precious memory you’ve loaded up your PC with.  This memory is even more critical in the 32-bit flavor of Vista, where most users cannot use more than 3.5GB of RAM, even if you have 4GB or more (read how to enable 4GB of RAM here).

How SuperFetch Works

After Vista loads its core, SuperFetch works by loading frequently used appliations and pages info a cache. Vista keeps track of which memory pages are frequently used (and which files they’re tied to) and will try to use up as much free memory as it can with what it analyzes you’re going to need soon.  SuperFetch keeps a history of how often and when you run applications, which influences what is cached.  This extra caching is what makes Vista’s memory requirements much greater than XP’s.

SuperFetch also monitors your current usage, so if it has to dump its cache for whatever reason, it will fill it up again once more memory is freed up. It can take a good amount of time to refill the cache, which means you’ll probably notice alot more hard drive activity even when the system is idle.  Previously, hard drive thrashing usually meant that Windows was “reacting” to low memory by pushing pages to Virtual Memory, but now this activity could be “proactive”.

Caching “frequently used” libraries isn’t anything new.  Even back in Windows 3.1 there were third-party programs that would cache DLLs in an attempt to increase system performance, but more often than not they ended up slowing the system down… it didn’t make sense to cache 4MB of DLLs on a system with only 4MB of RAM.  Granted, SuperFetch is alot more intelligent, but the principle remains the same: you need memory above and beyond your normal usage to see any benefit.

In theory, you could cache your entire hard drive if you had enough RAM, but most PCs today only have about 2GB.

Do you need it?

If you’re a multi-tasker, then SuperFetch does have significant performance advantages, but you need butt-loads of memory.  The performance advantages really only show themselves if you have more than 4GB of RAM, and because of that, you should be running a 64-bit version of Vista to see all of that extra RAM.

In our testing SuperFetch only offers performance enhancement if you have 4GB of RAM or more, and even then you only shave off fractions of a second when loading programs.  If you open up Task Manager you will probably notice very little Free Memory, and nearly half of it taken up as Cached.

Most of this cached information will be immediately flushed as you use your computer.  If you’re a gamer, then there really is no reason to fill up your RAM with stuff you’re not going to use.  Office users don’t really benefit that much, either, as any serious office user has frequently used applications in Startup.


  1. Mathew

    December 25, 2012 at 4:15 am

    "just say no to superfetch" … the though that superfetch isn't useful or it's decreasing system performance isn't on the right place… All free unused memory isn't good memory, without superfetch you are wasting it… When you using 40% of all amount of ram with datas and 60% aren't used you can cache it!… System is using HDD to fill ram only after boot for a while after that sometimes to precache… All memory that is cached is still "free", system can at any time rewrite it and use it if some program isn't loaded in memory by superfetch… Keep in mind that system shouldn't do it when you open app you are saving time by this

    • ocmodshop

      December 25, 2012 at 9:40 am

      As mentioned in the article, Superfetch can be useful if you have over 4GB of RAM. Back when this article was first written most people did not and received little benefit from it.

  2. Charleston

    June 20, 2011 at 10:32 pm

    Well, I'm a multi-tasker (also an avid online gamer) but Superfetch really don't bother me. I have only 893MB of RAM (128MB of shared video memory) and my computer still run smoothly.

    http: http://www.osnews.com story 21471 SuperFetch_How_it_Works_Myths

  3. the AxeMan

    June 20, 2011 at 10:32 pm

    i wonder if superfetch was designed to make the hard drives wear out fastr . o have noticed alot more hard drives failing in the first year of use.

  4. SPackie

    June 20, 2011 at 10:32 pm

    Free RAM is wasted ram? NONSENSE! Wasted RAM = SF caching applications that I rarely if ever use! Foreground apps and HDD get punished as a result of SF. How long does it take to open an app anyways?

  5. Erik

    June 20, 2011 at 10:32 pm

    Upgrading my PC from 4 GB. to 8 GB. actually slowed it down tremedously during startup due to hard disk activity. The culprit? SUPERFETCH! It was actually caching everything it could find, from video files, to database files, you name it. Disabling it was necessary because the hard disk access wouldn't stop for over an hour.

  6. Duncan

    June 20, 2011 at 10:32 pm

    If some of you took the time to research, you would find the internet littered with people having issues with SuperFetch after reboot. Sometimes 15-20 minutes of massive disk trashing. Disabling SF means I can use my laptop 2 mins after startup and I do not get a performance hit on starting applications that is noticeable. Good article.

  7. Nate

    June 20, 2011 at 10:32 pm

    Thanks Brian. I found your remarks helpful. Using Black Viper, and the Vistawired suggestions, I still have very slow boot-up. Will disable Superfetch and see if that helps.

  8. Rand

    June 20, 2011 at 10:31 pm

    Free RAM is wasted ram. It's a complete waste if you aren't filling unused ram with caches and buffers. The Unix world has been doing this for ages!

  9. Gusac

    June 20, 2011 at 10:31 pm

    totally absurd article..
    superfetch uses the algorithm and calculates the time,frequency of data program being used. so even if you're using it as workstation or a gamer, it won't be loading ram with unneccesary thing.. take it as a cache and not resource…
    Cache why? because it fills the 'free left' space with data prog that you mite need, if you really need soemthing that isnt in RAM, it will swap it!
    better get your facts straight dude.

    • Alan

      June 20, 2011 at 10:31 pm

      @Gusac: That's the theory… just like all of these tips, your mileage may vary. Your PC already has a lot of processes that waste more CPU cycles than they benefit the user. Try disabling superfetch and run benchmarks… some people notice an improvement. Better get YOUR facts straight… and run spellcheck.

  10. Flipburger

    June 20, 2011 at 10:30 pm

    Thanks for the great article! I was always wondering why my hard drive light never EVER went off after I upgraded to Vista. I disabled Superfetch and now my hard drive is much happier and Vista loads (from the login to the desktop) much faster when I boot up. A couple of seconds as opposed to almost 30 before. No kidding! Thanks again!

  11. brian

    June 20, 2011 at 10:30 pm

    that is such bull s*** i have 32 bit vista ultimate, running it with 1gb ram and its running perfectly. i can run itunes and a virus scan at the same time with no lag. try doing that in xp.

    • Tester

      June 20, 2011 at 10:31 pm

      @brian. Haha, oh my god iTunes and a virus scanner take SO much CPU cycles!!! I have Visual Studio IDE 2008, SQL Server 2008, BizTalk and a load of other services running simultaneously on XP Pro SP3 machine with 1 gig of ram on my old laptop without a hitch. I cannot even imagine running that on Vista with less than 4 gigs of RAM without it being the worst experience ever.

    • Laugh

      August 6, 2011 at 6:59 pm

      Thanks for the laughs… the could only be a joke… With 1 GB of RAM Vista barely even moves, let alone with Itunes AND a Virus scan running.

  12. Alan

    June 20, 2011 at 10:30 pm

    It says you MAY experience an improvement… most users really won't notice… just like most users don't notice one spyware program. But when a bunch of stuff is wasting cycles then you really notice.

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