Prefetch? On, Or Off?

[2010MegaScooter]

Prefetch? On, Or Off?

Dumb Question..
Is It Best To Have Prefetch Service On? Or Off? Does It Make Any Difference In Speed?
Thanks

 

[EzioAuditore]

It may or may not provide faster boot time but one thing it does is that it does speeds up the loading of programs you use. If you want to see the difference yourself, clear out the Prefetch folder's contents and reboot. I personally have it on but i do have Ccleaner to delete old prefetch files which doesn't contain much about my recent usage. Some articles you'd like to read: 1. http://www.jasonclarke.net/general/finally-windows-xp-prefetching-explained/ 2. http://www.edbott.com/weblog/2005/04/tip-of-the-day-dont-clean-out-the-prefetch-folder/ 3. http://windows.microsoft.com/en-US/windows-vista/What-is-the-prefetch-folder

 

[DeVandal]

In general, performance improvements provided by the Prefetch service far outweigh any performances provided by it's absence.

 

[pparks1]

I leave Superfetch and stuff on. Even with my SSD, coming from RAM is faster than coming from my hard drive.

 

[2010MegaScooter]

So, Imma Go Back To Regedit and turn it back on for the best performance


Yes?

 

[logicearth]

What ever guide you are following, Stop following it and reverse any changes you made.
Whatever it is, I can already tell the guide is filled with nothing but steaming pile of c*** advice.

 

[DeVandal]

Where did that come from? Even this forum has members who offer that tweak.

Just because it's on the menu doesn't mean you have to eat it.

 

[logicearth]

Where did that come from? Even this forum has members who offer that tweak.

Just because it's on the menu doesn't mean you have to eat it.

There is no valid reason to disable Prefetch. None. Even on an SSD drive Prefetch's index is invaluable. Disabling Prefetch solves no issues The only reason I have ever seen why someone says to disable Prefetch are those that do not understand what it does or is.

 

[DeVandal]

I agree that the tweak is misguided.

Let's assume three things are true:

• The tweak is invalid in many applications
• The source is steaming c***
• SF includes the tweak

What does that say about this repository? Dry factual presentation of solid guidance devoid of emotional rhetoric provides for a more reliable source.

 

[mickey megabyte]

i thought windows automatically disables superfetch if random writes and flushes are being performed fast enough, as per a fast ssd.

or is superfetch not the same as prefetch?

Will Superfetch be disabled on SSDs?

Yes, for most systems with SSDs.

If the system disk is an SSD, and the SSD performs adequately on random reads and doesn’t have glaring performance issues with random writes or flushes, then Superfetch, boot prefetching, application launch prefetching, ReadyBoost and ReadDrive will all be disabled.

Initially, we had configured all of these features to be off on all SSDs, but we encountered sizable performance regressions on some systems. In root causing those regressions, we found that some first generation SSDs had severe enough random write and flush problems that ultimately lead to disk reads being blocked for long periods of time. With Superfetch and other prefetching re-enabled, performance on key scenarios was markedly improved.

source

 

[pparks1]

Mickey,
Yes, it seems that with adequately fast enough SSD's, MS disables superfetch automatically. I guess I wasn't aware of that, I knew about defrag and stuff...but didn't realize myself that it extended to SSD drives.

 

[logicearth]

or is superfetch not the same as prefetch?

Prefetch is pre-Superfetch, it is what was in Windows XP. Prefetch is basically an index. It analyses what DLLs or other files an application loads up, the next time the application loads it can more optimally load all the required DLLs and other supporting files without waiting for them to be called.

Prefetch still exists in Windows Vista/7, Superfetch extends the capabilities of Prefetch.

Here is what Chrome's Prefetch looks like:

pf ver: 0.9
Tue, 25 Jan 2011 15:33:48 +0000 [GMT]

Analyzing file: C:\Windows\Prefetch\CHROME.EXE-33E7560A.pf

modified: 01/25/11 15:31:33
accessed: 01/05/11 03:41:03
created:  01/05/11 03:41:03

CHROME.EXE, run 1602 times, last run: 01/25/11 15:31:23.958

 --------- files mapped --------- 

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019 : \DEVICE\HARDDISKVOLUME2\WINDOWS\SYSTEM32\WTSAPI32.DLL
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022 : \DEVICE\HARDDISKVOLUME2\WINDOWS\SYSTEM32\MSCTF.DLL
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043 : \DEVICE\HARDDISKVOLUME2\WINDOWS\SYSTEM32\CRYPTBASE.DLL
044 : \DEVICE\HARDDISKVOLUME2\USERS\LOGIC\APPDATA\LOCAL\GOOGLE\CHROME\APPLICATION\9.0.597.42\PDF.DLL
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 --------- directories mapped --------- 

vol path:     \DEVICE\HARDDISKVOLUME2
time created: 08/24/10 12:59:22.000
serial num:   57ac-7fb2

001 : \DEVICE\HARDDISKVOLUME2\USERS
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003 : \DEVICE\HARDDISKVOLUME2\USERS\LOGIC\APPDATA
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[Wishmaster]

Automatic disabling of Prefetch does extend to most SSD Drives, unless they are lacking in the random read dept.
Most modern SSDs do not have that issue however.

Still, I too would agree that turning Pre-Fetch back ON, even on a SSD is worth the effort.
It still helps because, as already mentioned, reading from RAM is much faster than reading from, not only Standard HardDrives, but SSDs as well.

Keep in mind a lot of the tweaks to reduce writes for the SSD you'll see, were intended mostly for 1st Generation drives.
And secondly, the writes Pre-Fetch & Superfetch do, are quite insignificant.

If you have a Standard Hard Drive, certainly leave it ON.

If a SSD, your call. But, I would recommend leaving ON with them as well.