Myth Busted: Why Disabling SuperFetch on Vista and Windows 7 Is a Bad Idea
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March 3rd, 2010 written by Tibor in Myth buster
Let’s start this one off with a little, practical exercise. Are you with us? Good! Right-click on your taskbar, and select “Task Manager”. Now, take a good look at the numbers you see under the “Performance” tab. Let them sink in a bit.
This is unbelievable!
On a machine with 2 GBytes of RAM, how can there be 2 MBytes free? What’s behind all of this?
Even if you have twice as much memory, you will probably only have a couple of hundred MBytes available. This comes as an absolute shock to every computer user. While you’re only running a browser or listening to music, Windows Vista or Windows 7 consumes nearly all of your precious RAM. This fact led even Computerworld to pick up a Devil Mountain Software research study, claiming that Windows 7 maxes out memory and thus slows down the computer. To quote the research:
“On average, 86 percent of Windows 7 machines in the XPNet pool are regularly consuming 90 percent to 95 percent of their available RAM, resulting in slow-downs as the systems were forced to increasingly turn to disk-based virtual memory to handle tasks.”
Have you ever heard of SuperFetch?
The truth is—this is by design! Back in 2007, Microsoft introduced Windows Vista and one of its new features, SuperFetch, which is responsible for taking up as much of your computer’s memory as possible—albeit for a good cause!
- SuperFetch predicts which applications you will run next and preloads all of the necessary data into memory. It also does that with boot files. This helps prevent accessing the slower hard disk too often. The result? Programs launch much quicker, and Windows boots faster.
- SuperFetch’s prediction algorithm is able to determine which application users will open by a certain time of day and by a certain day of week. It is able to predict up to the next three applications that the user will launch.
- SuperFetch is smart—it prioritizes the programs you currently run over the background tasks, such as defragmentation. These tasks run when the computer is idle, but when they are complete, Windows SuperFetch populates the memory again.
- SuperFetch is dynamic—it adapts to your needs all of the time. So, if your favorite programs change over time, SuperFetch is able to quickly adapt to this.
Windows SuperFetch populates the computer’s memory with this preloaded information, to speed up programs and Windows features. So, what’s the benefit for you? Your favorite programs—for example, your Web browser, your media player and your e-mail application—are likely to start faster after a couple of days. Don’t worry, even if you install a new application, SuperFetch will not have a negative impact on performance. As soon as the new application demands memory, the SuperFetch data gets flushed. As far as this program is concerned, the memory is empty.
If you’re familiar with the Windows kernel, we recommend this interesting video from MSDN’s Channel 9. Michael Fortin from the Windows Performance Team talks about what Microsoft had in mind when developing SuperFetch and similar performance technologies. A little side note: Michael also talks about how a computer becomes slower over time due to the installation of a lot of programs (this is at about 20 minutes into the video). The TuneUp Blog team recently proved this theory in our post titled “How 200 Programs Slow Down Your PC“.
What happens when you disable SuperFetch?
Readers should know us by now. We don’t just talk theories; we test them intensely. So, we decided to disable Windows SuperFetch on one of our test machines and compare the performance of both machines. First of all, as expected, the Task Manager tells us that we now have about 600 MBytes of memory free.
This is bad! An important part of your computer is not being fully used. This is like having a 200hp engine in your car, with only 140hp being used. What impact did disabling SuperFetch have on our system? Boot performance went down immensely. Usually, this process took about one and a half minutes on our test bed; with SuperFetch disabled, boot time went up to exactly two and a half minutes.
We also compared the startup performance of a couple of applications, including Outlook 2010 Beta, which needed five seconds longer to start and navigating between folders felt sluggish. Launching even the very slim Google Chrome browser took about seven seconds, whereas the original test only took four seconds. This is not good.
Myth busted!
We can go on and on, but you get the point. Although we have more memory, performance actually noticeably decreased. SuperFetch in Windows Vista and Windows 7 is a good technology that helps speed up your entire system—and should not be disabled.
November 6, 2012 at 5:09 am
I suspect those who are very against superfetch are probably VMWare/VirtualBox/Parellells users.
The problem arrises when superfetch attempts to cache a large number of pages of a virtual disk file while a virtual machine is running. In the case of VMWare the hypervisor is looking for pages of guest memory which are not being used to swap out and return to the host. This in theory does increase performance, but in reality only a super high performance SAS hard drive like developers tend to have could possibly keep up.
Rather than disabling superfetch, it’s better to edit the regestry key HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management\PrefetchParameters and set it to 1 instead of 3. This causes only programs and DLLs to be added to the suprfetch cache giving you most of the benefits but preventing the contention problem. This is partly VMWares fault as they use a lot of nasty tricks, including doing their disk I/O from kernel mode so superfetch is not aware an application wants the disk.
If you are only running MS office you should not make this change or disable superfetch. For that scenario the article is correct. The main exception being ultraportable type laptops which have 1.8″ hard disks which can be unable to keep up in some situations, although this issue has been fixed in Windows 7 SP1, they now take into account the characteristics of the hard drive as well.
November 29, 2012 at 11:55 am
What about this Microsoft statement about SuperFetch and SSD ?
http://support.microsoft.com/kb/2727880
“SuperFetch and prefetch are storage management technologies in Windows that provide a fast-track access to data on traditional, slower hard drives. On SSD drives these really clever services only provide for unnecessary write operations. Typically, Windows 7 automatically disables these services for your SSD disk. Otherwise disable it manually.”
November 29, 2012 at 7:53 pm
On my machine, when I turn off the superfetch, everything just gets faster. In order to bust a myth, you’d better do your experiment on multiple machines with various setups. Otherwise, you are just misleading others with biased results
December 13, 2012 at 6:11 pm
If you have an appropriate amount of memory, you will not run into issues like this. People, have at least 3-4gb of ram. 2GB is not ok for any device with a full feature OS.
December 15, 2012 at 4:10 pm
I can verify that superfetch slows PC performance significantly. On a decent machine (>2GB RAM, 1TB SSD drive), the real myth is that superfetch is necessary. Turn it off and enjoy a performance boost!
December 16, 2012 at 5:47 pm
I was wracking my brain trying to figure out why my svchost.exe was eating up littlerly all of my processor and lagging the crap out of my computer. So I went through all of it’s services and played with them a bit.
After shutting off a few of the services I finally came to sysmain (or superfetch). At first, I thought it was a “needed” process, so I looked it up. After figuring that it was fluff, I disabled it. And immediately my computers performance tripled.
I’m not saying that it’s a spam process… but it’s a spam process. I would seem to me that it’s just a left over relic from Vista that they forgot to get rid of.
If it works for you, fine. But if you find your svchost.exe is destroying your processor, then I’d recommend shutting sysmain down and see for yourself.
December 31, 2012 at 6:09 pm
If I leave my Windows7 Lenovo t430 running over the weekend Superfetch gets a headache and runs my system at a crawl. Even restarting the service does not fix it. But if I stop the Superfetech service.
BAM! Back to full speed.
I’m thinking of disabling… Really don’t need a service that gives marginal improvement sometimes and slow me to a crawl the rest of the time.
January 4, 2013 at 7:42 pm
I had heard the Windows 7 SuperFetch and Prefetch were far better than the Vista ones, so I gave it another try. To test I used my standard load of programs, which includes processes that take a long time. The very simple measure of seeing how long it took LaTeX to compile a book, Visual Studio to compile a C++ program, and Blender to render a video segment were used after the computer had been up and running for about a month. In all three cases, as well as in simple operations with a word processor or other program, there was a massive, demonstrable improvement in performance after disabling the fetch systems.
When people have a sudden performance drop and they bring the computer to me, I try disabling these things if I find no viruses, etc. In some cases, not all, this causes the performance to return. My own testing and the results from these other computers tells me that Microsoft’s algorithm is simply flawed. I am quite certain it worked in their lab. However, it does not work for all people at all times. For some it causes problems. Microsoft needs to revisit this and make improvements.
January 24, 2013 at 2:45 am
Did anybody noticed that he/she miss read the task manager. He or she is looking at the free ram usage when in window7/vista it is not actually how much ram you have left.
February 25, 2013 at 12:06 pm
Superfetch made svchost.exe use over 500000 K Memory. Disabling this and it went down to under 50000 K Memory. Definitely disabling this and keeping it disabled!
February 25, 2013 at 7:04 pm
With the above comments in mind I also noticed the difference between the two screens of the task manager.
My biggest question is you go from 65 running processes(With Superfetch) and drop down to 49(Without Superfetch), why such a big change?
I’ll be doing my own testing once I’m at my desk.
But I however have little faith in M$ and would prefer as little be running as possible. So much bloat-ware has been added to help users have an “easier” experience. I miss the days when an OS ran only what it absolutely needed.
In the end though I’m sure my PC will have better performance once disabling this “service.”
March 11, 2013 at 8:46 am
OMG. I couldn’t figure out why my computer was stopping every 5 min to thrash the hard drive. Disabled superfetch. (I’m going to refer to it as stupidfetch now) and it stopped immediately. It’s not as ‘smart’ as the author claims.
my guess is that it steals all of the RAM from other applications so internet explorer runs faster.
March 17, 2013 at 4:00 pm
This article is very poor for the following reasons.
1) I dont care about boot time if the net result is a system which runs slower.
eg. Readyboot stops me from doing anything for 4-5mins and hacks my disk – I dont care about a few seconds faster boot. I only boot once and stay on for hours.
2) I dont care about program loading time. What I care about is the programs I am using having enough memory to efficiently run without getting paged out.
3) Fundementally flawed article. All that information has to be load from disk into memory using up both physical energy and wearing the disk. The information that is there isnt even required 99% of the time. Very, very poor use of resources.
March 29, 2013 at 7:36 pm
I am the IT department for a staffing company. I noticed a lot of our machines were running slowly, and the hard drives were thrashing when idling, to the point of using 100% of the disk drive. My searching led me to the svchost.exe application and superfetch. I disabled it and immediately saw a huge boost in performance. Please do not spread disinformation, this is no myth and superfetch presents very real issues for many computers.
April 13, 2013 at 8:33 pm
The Superfetch service works like it’s supposed to when the situation is right. I’ve had no problems with it. It most definitely improves system performance, just as this article states, when it is working properly.
#1, for smooth operation, you will need 4 GB of RAM in the computer. 2 GB does not work very well with Superfetch.
#2, if you have 4 GB of RAM and this service is causing the HDD to thrash and the system to be slow, it is an indication that the HDD is seriously fragmented. Unfortunately, most defragmenters simply remove fragments from files, strewing them like confetti all over the disk, instead of putting them in order. This means that the HDD will have to go on a “confetti hunt” as it tries to find frequently used system files. At this time, I cannot recommend a particular defragmenter, because I need to do more testing; however, you might want to give “MyDefrag” a try.
April 26, 2013 at 12:49 pm
You have to give a tube radio at least 20 to 30 minutes just to
warm up and then you decide what frequency you want to be on and load the plate and tune them up.
Next, build a list of prospects and develop a relationship with those prospects on your list.
Perfect for long trips and for up to date information on road conditions ahead.
April 26, 2013 at 2:25 pm
Meet Ira – Our Wi fi Internet radio adapter that connects
automatically to any wireless Internet network.
Remember that most dorm room radio stations out there may or may not be online from time to
time and that cannot be blamed on the app,
however this does hinder the experience of
Internet radio on the i – Phone. ” Many of these people knew that drugs were wrong, but elected the easy route of following the popular opinion.
April 27, 2013 at 2:30 pm
Believing that you are actually starving, it releases chemicals that actually make
it harder to lose weight in an effort to conserve energy.
Withdrawal from levothyroxine can be done but it takes 6 weeks
of withdrawal for the remaining thyroid tissue to be completely starved.
Who does not need that little bit of elevation when trying to diet.
April 29, 2013 at 1:02 am
Superfetch VERY BAD! Cached ram is NOT free ram, programs cannot make this distinction. I’ve had programs refusing to run because it says I have no free ram, which of course is false. I got 8 gigs so nothing like this shouldn’t have this happening.
May 5, 2013 at 3:55 pm
It is the A Funeral Poem which can lift the soul of these small children, though they may not even know what death means.
Friendship Collection: a beautiful selection of friendship audio poems to share with your closest friends.
On the other hand children spend most of their time with their mothers, who love deeply, scold harshly, they worry extremely
but in the end they make you what you are.
May 11, 2013 at 5:17 pm
Try simple games and check how your internet connection is and then move on
play more games. Say you’re doing as well at Chemistry, and as you are doing at Maths Extension 2, then instead of splitting your study time equally between the two (just because they are both worth 2 units each), you should spend more time on Extension 2, simply because it scales higher. For the purposes of this game, a “set” is at least three cards of equal value such as three Jacks or three fours and a “sequence” is made up of at least four cards that are of the same suit and run sequentially such as three, four, five, and six of spades.
May 11, 2013 at 7:58 pm
nice spam losers.
clean up your stupid site