Solved To Prefetch, or not to Prefetch?

TM21 · Jan 2, 2023

Prefetch is something I've not thought about in years. However, years ago it was a topic of much discussion and contention.

Has it outlived its usefulness, or is it still important?

Does anyone still empty their Prefetch folder as a part of regular maintenance?

DigitalGoat · Jan 2, 2023

I looked into this a while back, when Intel sold thier SSD division to Solidgm (spelt right I think), the advice from both companies, who make both the hardware and drivers, was to leave Windows caching alone due to changes in the way SSDs, the firmware and Windows works.
So for me I don't bother altering anything cache wise, no cleaning out of a folder that 'should' maintain itself and no disabling of Sysmain.
You are bound to get a variety of answers here on this subject but IMHO if the manufacturers of your hardware suggest making no changes, then that is the way you should go.

PerpetualCycle · Jan 2, 2023

TechnoMage2021 said:
Prefetch is something I've not thought about in years. However, years ago it was a topic of much discussion and contention.

Has it outlived its usefulness, or is it still important?

Does anyone still empty their Prefetch folder as a part of regular maintenance?

No, prefetch is still useful and doesn't take that much disk space. I even use it although I have block level disk caching software that persists across boots and cache most all of programs.

EDIT: Also you can disable it through the registry so you don't have to clear it out.

Berton · Jan 2, 2023

Interesting, on Win11 putting prefetch in the Search box on Start brings up a few things that mostly deal with Win10 but the first is to bring up the Start, Run box and putting in the word brings nothing up.

TM21 · Jan 2, 2023

Honestly, I had not even thought about Prefetch, since Windows XP, where I had it listed in my XPCleanup.bat program.
Since then it's been like City Water, out of sight and out of mind.
But it's still pretty much right where is always was:
C:\Windows\Prefetch

It's weird though, because I found it a few days go, emptied it and then sat there and watched it start to fill up again. And I was doing nothing.
After a few days, it will have hundreds of files in it, and take up many megabytes of space.
So what's it really doing to make Windows better?
There were many things we did years ago, to offset the slow speeds of the old spinners, that we don't need to do today.

garlin · Jan 2, 2023

Pre-fetch will provide no benefit on any SSD drive, because the seek time for any random block is the same on every block. On a slow HDD, pre-fetch creates a defragged cache of commonly used system files to minimize load times.

The real problem is pre-fetch never tells you if the effort made any difference, because it provides no timings or stats.

TM21 · Jan 2, 2023

I know it's simple to empty the Prefetch folder, but, is there a way to just turn off the feature? If I ever knew, I've forgotten.
I wrote a little batch file that empties the Prefetch folder:
@Echo off
cls
del /F /S /Q "%systemroot%\Prefetch\*.*" >nul

PerpetualCycle · Jan 2, 2023

garlin said:
Pre-fetch will provide no benefit on any SSD drive, because the seek time for any random block is the same on every block. On a slow HDD, pre-fetch creates a defragged cache of commonly used system files to minimize load times.

The real problem is pre-fetch never tells you if the effort made any difference, because it provides no timings or stats.

There is two parts to prefetch. One is defragging files used for boot so they are sequential so you get a faster boot. For this what you said is true.
The second is preloading frequently used files into memory at boot in anticipation of their use by the user, so that they load faster. Memory is still faster than and SSD.

PerpetualCycle · Jan 2, 2023

TechnoMage2021 said:
I know it's simple to empty the Prefetch folder, but, is there a way to just turn off the feature? If I ever knew, I've forgotten.
I wrote a little batch file that empties the Prefetch folder:
@Echo off
cls
del /F /S /Q "%systemroot%\Prefetch\*.*" >nul

Yes, I said there is in the registry. You can google to find it.

Bree · Jan 2, 2023

TechnoMage2021 said:
I know it's simple to empty the Prefetch folder, but, is there a way to just turn off the feature? If I ever knew, I've forgotten.

This....

This tutorial will show you how to enable or disable SuperFetch (SysMain) in Windows 7, Windows 8, and Windows 10.

You must be signed in as an administrator to enable or disable SuperFetch.

This will affect:

- Prefetch
- SuperFetch
- RAM compression
- ReadyBoost

Enable or Disable SuperFetch (SysMain) in Windows

How to Enable or Disable SuperFetch in Windows

www.tenforums.com

TM21 · Jan 2, 2023

Apparently, in "Services.msc" the 'SysMain' service is the one that is responsible for saving files to the Prefetch folder.
Unless, it's not!

I just disabled it, so we'll see......

TM21 · Jan 2, 2023

Experimenting, , , I just ran Services.msc, and I found the SysMain service and disabled it.
I've opened the 'Prefetch' folder and so far, I've seen NO NEW files listed there.
And lo and behold, my PC is still running.

Bree · Jan 2, 2023

TechnoMage2021 said:
Experimenting, , , I just ran Services.msc, and I found the SysMain service and disabled it....

Yes, that works, it's Option One in Brink's tutorial that I linked to in post #10

TM21 · Jan 2, 2023

Meaning no disrespect, but I didn't need a tutorial.

Thanks guys, for a very welcome dialog!

Bree · Jan 2, 2023

TechnoMage2021 said:
Meaning no disrespect, but I didn't need a tutorial.

Just confirming that you found the same solution as Brink

TM21 · Jan 2, 2023

Apparently, in "Services.msc" the 'SysMain' service is the one that is responsible for saving files to the Prefetch folder.
Unless, it's not!

I just disabled it, so we'll see......

TM21 · Jan 2, 2023

Once in a while, I get lucky, but Brink is still my "Super Guru".

cereberus · Jan 2, 2023

In the end, a older slow hdd will benefit more than a modern fast ssd.

It was probably more important a few years ago than now.

In the end, it is easy enough to turn it off but I have never found a situation where
tirning it off improves things.

The old adage always applies "If it ain't broke, don't fix it*.

TM21 · Jan 2, 2023

True, you may not want to fix it, but maybe just give it a fresh coat of paint and make it look better. lol

Just a thought...is your car broken when you take it in for an oil change? No. That's just good maintenance
I maintain my PC by cleaning out files that I don't need, then they don't have to be scanned over and over again, and stuffed into my weekly backups. A wise man once said, "minus krud is cool".

PerpetualCycle · Jan 2, 2023

TechnoMage2021 said:
True, you may not want to fix it, but maybe just give it a fresh coat of paint and make it look better. lol

Just a thought...is your car broken when you take it in for an oil change? No. That's just good maintenance
I maintain my PC by cleaning out files that I don't need, then they don't have to be scanned over and over again, and stuffed into my weekly backups. A wise man once said, "minus krud is cool".

That is not a good analogy IMO. Changing oil is a preventative measure that reduces wear on your engine. Disabling prefetch prevents nothing. If you don’t change your oil your engine will get damaged. Scanning and backing up prefetch data will have no noticeable impact on time or storage.

Solved To Prefetch, or not to Prefetch?

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