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because (non-old) prefetch is in use and thus locked, this would be my guess.

 

This is a false guess.

 

I have safely used Windows delete to delete the entire contents of the prefetch folder numerous times under both XP & 7 without ill effect.

This would be impossible if they were locked & in use. CCleaner only deletes old entries, & prefetch contents are not locked.

 

Also, @Keatah, while true that you do have to be careful what you delete in some things he listed, prefetch isn't one of them.

It is safe to delete the entire contents of the folder.

 

Windows will automatically re-create them as needed, unless prefetch is disabled.

Honestly, I cannot tell a single bit of difference with it off or on, as human observable performance appears identical.

 

As CCleaner was created to clean trash, not speed up the PC, I would much rather be given the option to delete the entire prefetch folder contents.

 

3.24 of CCleaner under 32 Bit 7 cleared the entire prefetch folder when I added it to includes. You may have to edit/include files & subfolders option.

 

* Prefetch & IE caches both have identical purpose. Speed loading time. As CCleaner cleans IE caches for privacy, not speed, I'd consider prefetch trash...

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Guest Keatah

I like how CCleaner addresses the prefetch folder currently. If you want to blast the entire folder, then just add an INCLUDE entry. That's what that option is for. Of course you know that.

 

Now,

I found that MsiZap (from M$) will go through the "C:\WINDOWS\Installer" folder and compare the uninstall information there with what you have actually installed (derived from the add/remove programs list). It will compare and delete orphaned entries. It is command-line driven and thus technical in nature (gasp!). I tested it on my junk system, now I'm going to backup a mission critical system and retest it again.

 

It will be interesting to see how much install & uninstall (msi installer files) stuff is orphaned on a well used 10 year old xp install that has been meticulously maintained. I would guess out of the 1.7GB, that perhaps 500MB is unattached & orphaned garbage. I am anticipating that this 500MB chunk is data that will never ever EVER be used again and is thus candidate for deletion. It will never be read, or accessed or referenced in any way shape or form.

 

Now, thinking about the DLL CACHE, isn't that something microsoft puts there as a safety net? Something that windows can fall back on if a DLL gets corrupted or deleted? This, too, is a candidate for orphan searching. I wouldn't feel comfortable deleting the whole directory contents. But perhaps just stuff that is no longer used. Again, another great candidate for an orphan-scanner-style of cleaner.

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Guest Keatah

I do all my system maintenance with a simple philosophy in mind. And that means -- "What can I do to lighten the load.." or how much internal "behind the scenes" work is being done to make stuff happen. In the case of prefetch, just turn it off. No reason to create the files only to delete them later. To keep doing this goes against my methodology of keeping a system smoothly running.

 

It also bears mentioning that as the computing ecosphere continues to advance, buffers and caches just keep getting more common. Your modern i7 has all sorts of temporary holding spots going on, especially with the integrated graphics. You've got L1 + L2, data/instructions, L3, TLB, ring buffers, GPU texture cache, shader instruction caches. You've got windows setting up all kinds of caches on disk and in RAM, fonts, MFT & file system stuff. And there's cache on the hdd and nic too. In yo' printer, and even triple buffering for your monitor. Better not forget the soundcard and USB ports either. Pagefile.. and more! The stuff's everywhere!

 

All this.. stuff.. All this serves to bury latency. And that's a good thing. And it is also why many tweaks do little or nothing for speed. It all gets lost in constant shuffling. So the best way to tweak a system is tone down how much stuff you push around. And if deleting Prefetch means windows will recreate it, that's a negative tweak. You can probably turn it off, like I said before. But then windows and your CPU, together, will spend extra time figuring out the best load configuration for a given application. This process will happen every time you load an app without a .PF file.

 

So CCleaner's approach is best. Kill the .PF files no longer in current use, and lighten the load on the disk subsystem by a couple hundred kbytes. Any other approach and you're generating megabytes of extra bus activity. Yep.

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And if deleting Prefetch means windows will recreate it, that's a negative tweak. You can probably turn it off, like I said before. But then windows and your CPU, together, will spend extra time figuring out the best load configuration for a given application. This process will happen every time you load an app without a .PF file.

 

So CCleaner's approach is best. Kill the .PF files no longer in current use, and lighten the load on the disk subsystem by a couple hundred kbytes. Any other approach and you're generating megabytes of extra bus activity. Yep.

 

Windows will also create new PF files all the time for the new programs you use, while pushing out the old.

Since I use new files all the time, I'd hardly say this is a time saver. So you could call PF a negative on my system the way I use Windows.

 

And mb of extra bus activity is hardly a strain, considering the gb of data downloaded with thousands of tabs open.

 

Prefetch vs temp caches... Why clean em? Let's just leave IE caches & only update new information off the web. Save a few GB traffic.

 

-> Is installing 1,000 files to test a week good for PF generation? -_-

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Guest Keatah

Sweet jesus babycakes! I finished the backup, and ran msizap (free from m$). It found a honk'n 355 meggerz of orphaned install files. Just about what I guessed. These would probably come from a non-standard abort (or sloppy programming) of an install package. These are files that I suspect will never be accessed again under normal operation during the life this system.

 

The files are large, 15 megs each and many are the same. In going through them, I think they're related to Java offline installer. There's references to Oracle and Java and some shovelware toolbars and other advertising inside them. I cross-correlated them against LastActivityView from Nirsoft and my maintenance notes and found I had a Java issue on the same day these files were created. I'm fully satisfied of the origin and original purpose of the files and am not going to investigating any further. No need to tear into them in any great detail.

 

I checked the files it didn't touch, and they are all related to existing installed apps.

 

It's always been a nagging concern of mine - what happened to those aborted Java installs! Ohh wow.

 

For the CCleaner team:

Perhaps this could be an additional feature, Remove Orphaned Installer Cache Files. After all, CCleaner does this to invalid & orphaned Shortcuts. Similar concept here.

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As far as I know prefetch files are some sort of indexes used for altering the way applications (and boot files) load. I think they are quite good at minimizing DISK CACHE MISSES with regular HDDs. Do not empty your prefetch folder. The prefetching works quite well and it seems even better on Vista/7 when compared to XP.

 

Doing some tests with Apptimer, a nifty free app, I have noticed loading time speedups up to 500% for certain applications. My harddisk is not the fastest out there, too. So prefetch, does work indeed and it does work well.

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Doing some tests with Apptimer, a nifty free app, I have noticed loading time speedups up to 500% for certain applications. So prefetch, does work indeed and it does work well.

 

Wonderful!!! Just imagine how great HDD webpage caches work? 5,000% faster load? Perhaps?

_____

 

Each time you CClean your internet caches, you are removing files that greatly speed up page access, since they are retrieved locally.

 

The danger of CCleaning, is your removing the optimization, & when you visit the same page in the future, it will just be recreated all over again, anyway.

Only, a lot slower, since it will have to re-download the files off the web. Instead of only updating the changes since last visit.

 

Who wants to de-optimize web access? This can result in GB more traffic than before...

_____

 

The purpose of CCleaner is not to optimize, but to reclaim free space & (hopefully) aid in privacy. -_-

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I found that MsiZap (from M$) will go through the "C:\WINDOWS\Installer" folder and compare the uninstall information there with what you have actually installed (derived from the add/remove programs list). It will compare and delete orphaned entries. It is command-line driven and thus technical in nature (gasp!). I tested it on my junk system, now I'm going to backup a mission critical system and retest it again.

 

Microsoft themselves discontinued it because it could cause serious issues. Albeit it's still included with some antivirus packages.

 

Edit:

If you're expecting MsiZap to perform miracles with space saving which was something I thought several years ago too, in my case it found a mere 5MB of junk. However that may be because I use Total Uninstall to remove as much of an application during uninstall. I do however know allot of software that was compiled with Windows Installer will leave behind .msi files, etc., in the "Windows\Installer" folder after using the included uninstaller, some of which can be huge.

Edited by Andavari

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Now, thinking about the DLL CACHE, isn't that something microsoft puts there as a safety net?

 

That folder is there for System File Protection, also helps avoid "DLL Hell".

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Guest Keatah

DLL CACHE - yep, it's not a temporary cache like a buffer. It is a storehouse, like a geocache.. As part of safe cleaning practices it's a no-no don't touch.

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Prefetch is totally safe to clear the whole folder.

 

But, Cap'n Spectacular is totally right about DLL cache, & MSI zap...

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Hi,

 

 

After some tests, I can say that I spoke too soon.

 

We may have a problem emptying WINDOWS\SoftwareDistribution\Download.

For WINDOWS\system32\dllcache, I have not yet found. It is used to replace important files deteriorating. It does not ever happened to me.

 

Do not just empty, but only a part. Which one?

 

Bests regards

 

R G

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I'd say probably your DLL cache is the one to avoid emptying.

 

It is part of Windows File Protection (replace deleted system files).

 

If you just want to know why it won't fully empty, see Keatah's post below.

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Guest Keatah

C:\WINDOWS\SoftwareDistribution is related to automatic updates. Delete it and auto-update will recreate it.. minus the previous files.

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Guest Keatah

You also need to stop AU and BITS services, otherwise I believe they lock the folder.

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Hi,

 

 

Thank you for your answers.

 

I use my computer very differently from you. I disable all: Trash, restore (System Volume Information), CISV, cidaemon, automatic updates, pagefile, hyberfile, minidump, ...

 

I do not have the same reaction of the computer.

 

Best regards

 

R G

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I thought just last week that deleting everything in the SoftwareDistribution folder which was something I never did before would give me more free disk space after nearly three years of accumulation on this XP install. And I was completely wrong, because after a reboot and visiting the Microsoft Updates site it was right back at the exact same size in MB where it was before - epic fail!

 

I do however use Dial-A-Fix (currently for WinXP only) to safely clean it, using the "Yes" option that leaves the DataStore.edb file intact.

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Hi, Andavari

 

We don't have to empty Software, but Download. It should also disable automatic updates.

 

As was said in the American movie, War Game, with computers, it is dangerous to remove human intervention.

 

Best regads

 

R G

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I agree that auto updates is the devil.

 

Auto updates will download all kinds of pesky things, such as a spyware application to always check if your system is "legit".

This may be great for MS, but I hate the "always a camera in my face because you may be a criminal" attitude they are fronting.

 

I mean, if someone does a crime, do the time, but don't treat everyone like criminals! LOL!

 

I hate to have Windows Updates prompt for reboot right when I am in the middle of an important task that needs to complete so I won't lose data.

Manual updates is better for me, because I get to choose what & when it's updated.

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