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The Windows Prefetch Folder


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#1 unloaded

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Posted 27 September 2006 - 03:35 AM

is there a way that I can permanently set the windows prefetch folder so that it does not add more and more files to itself?

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#2 HitSquad

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Posted 27 September 2006 - 04:52 AM

You can modify the prefetch parameters via the reg at HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management\PrefetchParameters.
Use a DWORD Value with either of the following hexadecimal numeric values:
0 = Disabled
1 = Application Launch Prefetch
2 = Boot Prefetch
3 = Prefetch All
I do not use the prefetch function myself and have it set to 0.
Before you do the above, delete the contents of the prefetch folder itself first.
You will want to shutdown any running apps that are using the prefetch folder as well.
After you make the reg change, a reboot is required.
You can test the different settings to see which one you prefer by seeing what goes back into the prefetch folder afterwards.

#3 Enthusiast

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Posted 27 September 2006 - 05:08 AM

By default, the prefetch folder is set for Windows to keep it to 128 entries over three weeks, and it isn't files in full but a directory os where files are so Windows can find them quickly instead of scanning your hard drive every time you start an ap, etc.

Pruning or cleaning it yourself, or limiting it will cause your aps to take longer to open.

Read the following before you mess with it:
Prefetch warning and links
http://www.edbott.com/weblog/archives/000743.html
http://www.langa.com/newsletters/2005/2005-04-07.htm#3
“PreFetch”
http://langa.com/newsletters/2003/2003-09-22.htm#7
Prefetch Pros and Cons
http://langa.com/newsletters/2002/2002-12-12.htm#9

"I've found many web sites recommending a way of speeding up boot times that might in fact slow down the amount of time it takes to boot up and will probably slow down launching applications as well. The tip recommends going to your C:\WINDOWS\Prefetch directory and emptying it every week. Windows uses this directory to speed up launching applications. It analyzes the files you use during startup and the applications you launch, and it creates an index to where those files and applications are located on your hard disk. By using this index, XP can launch files and applications faster. So, by emptying the directory, you are most likely slowing down launching applications. In my tests, I've also found that after emptying the directory, it takes my PC a few seconds longer to get to my desktop after bootup."
http://www.langa.com/newsletters/2005/2005-04-07.htm#3



XP systems have a Prefetch directory underneath the windows root directory, full of .pf files — these are lists of pages to load. The file names are generated from hashing the EXE to load — whenever you load the EXE, we hash, see if there’s a matching (exename)-(hash).pf file in the prefetch directory, and if so we load those pages. (If it doesn’t exist, we track what pages it loads, create that file, and pick a handful of them to save to it.) So, first off, it is a bad idea to periodically clean out that folder as some tech sites suggest. For one thing, XP will just re-create that data anyways; secondly, it trims the files anyways if there’s ever more than 128 of them so that it doesn’t needlessly consume space. So not only is deleting the directory totally unnecessary, but you’re also putting a temporary dent in your PC’s performance. [emphasis in original]

Bottom line: You will not improve Windows performance by cleaning out the Prefetch folder. You will, in fact, degrade Windows performance by cleaning out the Prefetch folder. I’ve done performance testing that establishes this definitively. In all the many sites that offer this bogus tip, I have yet to see a single piece of actual performance testing.
http://www.edbott.com/weblog/archives/000743.html

#4 unloaded

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Posted 27 September 2006 - 11:26 PM

you said that the prefetch folder is set for Windows to keep it to 128 entries over three weeks, so is there a way to set it lower?

#5 acklan

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Posted 28 September 2006 - 12:53 AM

If I may ask, why do you want to modify the Prefetch Folder? Are you having a problem that you feel will be solved by eliminating the files in th Prefetch Folder?
We are here to help if you give us a chance. From what Enthusiast has provided it would not help to simply delete the files.
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#6 unloaded

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Posted 28 September 2006 - 06:45 AM

i want to modify it because I know there is only one file thats essential to quicken the startup process. and I would like to set that folder to keep the file only and do not automatically add other prefetch files itself, thats all.

#7 usasma

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Posted 28 September 2006 - 11:22 AM

Since you're concerned with the startup process, I'd suggest using HitSquad's first post to you and setting the DWORD value to 2.
My browser caused a flood of traffic, sio my IP address was banned. Hope to fix it soon. Will get back to posting as soon as Im able.

- John  (my website: http://www.carrona.org/ )**If you need a more detailed explanation, please ask for it. I have the Knack. **  If I haven't replied in 48 hours, please send me a message. My eye problems have recently increased and I'm having difficult reading posts. (23 Nov 2017)FYI - I am completely blind in the right eye and ~30% blind in the left eye.<p>If the eye problems get worse suddenly, I may not be able to respond.If that's the case and help is needed, please PM a staff member for assistance.

#8 Enthusiast

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Posted 28 September 2006 - 12:08 PM

You only want it to list ONE application or Windows process?

That would greatly lenghten the time that your system takes to boot and your applications to open.

You obviously do not understand what I posted earlier -

By defeating the prefetch defaults you will be adversely affecting the way Windows XP is designed to work.

Read the description of prefetch again in my post above - it is simply a directory of where files you use most often are on your hard drive that Windows manages and limits to 128 entries automatically, and uses instead of having it necessary for Windows to scan your complete hard drive any time a system process was needed or you opened an ap. It is not a compilation of complete files that take any serious amount of space on your hard drive.

#9 unloaded

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Posted 29 September 2006 - 12:11 AM

thats not what i meant exactly; I clean my prefetch folder regularly, but I leave only one pf. file in the prefetch folder, which it does speed up my computer boot process. if I have other pf file left in the folder eg. for antivirus, it will help to open up the application faster but that will slow down the bootup process, however if I clean the entire prefetch folder, that will slow down the boot process as well. Which the pf.file i leave in the folder is called NTOSBOOT-B00DFAAD.pf. It helps the windows start much faster. and i want to modify the prefetch folder because I know only that pf.file will quicken the startup process. and I would like to set that folder to keep the file only and do not automatically add other prefetch files itself, thats all.

#10 Enthusiast

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Posted 29 September 2006 - 06:24 AM

Prefetch warning and links
http://www.edbott.com/weblog/archives/000743.html
http://www.langa.com/newsletters/2005/2005-04-07.htm#3
“PreFetch”
http://langa.com/newsletters/2003/2003-09-22.htm#7
Prefetch Pros and Cons
http://langa.com/newsletters/2002/2002-12-12.htm#9

#11 unloaded

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Posted 01 October 2006 - 02:55 AM

none of these links tell me how to modify the prefetch folder.

#12 Enthusiast

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Posted 01 October 2006 - 03:12 AM

It is your computer and if you want it to start faster but take much longer opening any ap after you start the computer it's your perogative.

It is a very foolish thing to do though.

Hitsquad described exactly what you need to do to accomplish what you say you want.

#13 unloaded

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Posted 01 October 2006 - 07:39 PM

He post how to change the registry, which I already know that it is useless (no offence), but my question was to ask for a way to change the setting of the prefetch folder so that it does not keep on adding pf.files itself. If there's no solution, thats fine.

#14 usasma

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Posted 01 October 2006 - 08:06 PM

From what I've seen in my research, there doesn't appear to be a way to limit the prefetch behavior like you want to. The only options that you have are the options that HitSquad mentioned in post #2 of this thread.
My browser caused a flood of traffic, sio my IP address was banned. Hope to fix it soon. Will get back to posting as soon as Im able.

- John  (my website: http://www.carrona.org/ )**If you need a more detailed explanation, please ask for it. I have the Knack. **  If I haven't replied in 48 hours, please send me a message. My eye problems have recently increased and I'm having difficult reading posts. (23 Nov 2017)FYI - I am completely blind in the right eye and ~30% blind in the left eye.<p>If the eye problems get worse suddenly, I may not be able to respond.If that's the case and help is needed, please PM a staff member for assistance.

#15 unloaded

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Posted 01 October 2006 - 11:42 PM

ok, thk u VM.




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