Cleaning the Prefetch Folder Tweak

[klumy]

CCleaner - Recently CCleaner has added a performance slowing cleaning option, cleaning "Old Prefetch Data" enabled by default. Cleaning the Prefetch folder is a Myth and actually hurts performance. Do not select this option for cleaning as it will increase application and Windows load times. At the very least this option should not be enabled by default and a warning given if selected. I have contacted the makers of CCleaner unsuccessfully and have had subsequent topics brought up on their forums locked or deleted. For such a great program to turn a blind eye towards its users is unacceptable. I look forward to the makers of CCleaner to rectify this situation. - Source

 

http://mywebpages.comcast.net/SupportCD/XPMyths.html

 

Would i be better to leave this function out of Ccleaner?

[Spysnake]

Actually CCleaner cleans only "old" prefetch files, as name of that function says. Cleaning whole folder indeed slowes loading times dramatically after reboot. However, I think that this cleaning is safe for use.

[TwistedMetal]

Well, this could easily turn into a flamer's thread, but here goes....

 

People have argured over this since the release of Windows XP, could deleting prefetch files slow down your PC? Yes and no.... Deleting system prefetch files "can" slow down your startup time, by a matter of 2-5 seconds (dear god I can't wait 5 whole seconds)... Deleting application prefetch files "can" slow down the application startup, by milliseconds (again, I have no time to wait milliseconds).

 

I would clean Prefetch, but only ever 2 or 3 months, as it can take up disk space, and there could be old prefetch files from programs you have uninstalled. The prefetch will build back up, but it could take several reboots to do it. There has also been rumors (a few on this thread) removing the prefetch files crashed their programs. I highly doubt it, prefetch is an setting in Windows XP, and it can be disabled. So, I doubt prefetch makes that much of a difference in the operating of Windows XP.

 

F.Y.I - Me and MrG have been talking, and he is probably going to do something different with Prefetch in CCleaner, in the next release.

[Glenn]

Since Windows XP is supposed to delete old Prefetch files automatically when the 128 file limit is reached, using CCleaner to clean them a little sooner should have very little effect.

[TwistedMetal]

What Is Prefetch?

 

Taken From Microsoft Website:

 

Windows XP monitors the files that are used when the computer starts and when you start applications. By monitoring these files, Windows XP can prefetch them. Prefetching data is the process whereby data that is expected to be requested is read ahead into the cache. Prefetching boot files and applications decreases the time needed to start Windows XP and start applications.

 

This information is logged and stored on your hard drive taking up space and requiring a process to be kept running monitoring which applications are being run. This has a performance impact on your PC. Disabling the Prefetch function or at least only enabling it for the Boot Files will allow you to free up some system resources and preserve some disk space.

 

Windows XP automatically optimizes itself every three days.

 

If you want to control your Prefetch, I recommend downloading this: http://www.majorgeeks.com/download.php?det=2495

[DjLizard]

klumy: The answer to your question is yes.

[klumy]

at least, there should be a hint to show that this checkbox affect the performance.

 

So the user can decide what he wants

 

performance or free space !!

[Tarun]

It doesn't hurt your performance at all. It removes old unused prefetch files that over over 2 months old (I believe).

[DjLizard]

The point is, this has nothing to do with speeding up your computer or assisting privacy (which I thought were CCleaner's points of interest), and deleting "old" prefetch entries (which XP would delete to make room for more anyway) really does nothing except free one or two hundred KB.

[Tarun]

The point is, this has nothing to do with speeding up your computer or assisting privacy (which I thought were CCleaner's points of interest), and deleting "old" prefetch entries (which XP would delete to make room for more anyway) really does nothing except free one or two hundred KB.

 

Yeah. With today's hard drives that amount really means nothing.

[Greenknight]

Basically, it's a very minor matter either way. The author of that site just likes to stir up controversy to generate more hits on the site. He wastes everybody's time with this garbage, best to ignore him.

[DjLizard]

Actually, now that it's been tweaked, that page is quite informative and accurate (including the Firefox myths).

[JDPower]

Well I have always had the old prefetch box ticked but having read THIS extremely informative page, linked to on the above site, it is now unticked and will stay that way. Thanks to klumy for bringing up the topic for debate.

[Humpty]

I have Ccleaner set to clear any old prefetch items.

 

Actually I go in and delete any entries left behind after I try out an app and uninstall.

 

You should take note of the layout.ini file within prefetch.

 

Quote from Perfect disk which I use:

 

By default, Windows XP monitors application launches and identifies those files loaded during the process. Windows stores this information in the prefetch folder (usually Windows/Prefetch) in a file called layout.ini. Every 3 days, Windows does a "partial" defrag of the files indicated in layout.ini - attempting to make sure that they are contigous so that your system will boot faster and applications will launch faster.

 

If PerfectDisk has been configured to let Windows manage the boot files, PerfectDisk will mark the files indicated in layout.ini as unmovable and will not attempt to defragment these files or move them elsewhere on the drive as it is expecting Windows do perform this task every 3 days. This can prevent PerfectDisk from doing a complete defrag job.

 

If PerfectDisk has been configured manage the boot files, PerfectDisk will read layout.ini and will make sure that the files indicated are contiguous and the location is optimized

 

As PerfectDisk is a much more powerful disk defragmenter than the built-in defragmenter, letting PerfectDisk manage the boot files will ensure that these files are optimized for the fastest possible performance.

[pwillener]

Well I have always had the old prefetch box ticked but having read THIS extremely informative page, linked to on the above site, it is now unticked and will stay that way. Thanks to klumy for bringing up the topic for debate.

Prefetching Facts

8. The Prefetch folder is auto cleaned after 128 entries have been reached.

 

So far no one who writes on the subject has explained how the prefetch folder is cleaned. FIFO? Least frequent used?

 

I would really like to see an explanation why Windows prefetch cleanup is better than Ccleaner.

[Glenn]

I've only had Windows clean up Prefetch once when I had a good idea of what happened. My observation for what it's worth:

 

The number of files in Prefetch reached 129 (128 .pf files + Layout.ini). The next time I looked (after a reboot for other reasons), only 64 .pf files + Layout.ini remained. It looked like it was FIFO but of course the boot prefetch items had become the most recent.

 

I don't know if the reboot was necessary or if it would have cleaned without.

[pwillener]

Thanks for your observation - that's very interesting!

 

I just had a look at my prefetch folder and found that it contains 64 items (+ layout.ini), and nothing is older than 3 days.

 

To me it looks like that uproar about Ccleaner (optionally) deleting prefetch items older than 2 months is really a lot about nothing.

 

Furthermore I am wondering... if an application is uninstalled, but already has items in the prefetch folder, do these items eventually disappear, e.g. on a system where the 128 max is never reached?

 

 

P.S. just found some basic information on the prefetcher at http://en.wikipedia.org/wiki/Prefetcher