Mastertech

No it is not, what he said is not happening nor should it even if it was doing what he said it should be: CCleaner is removing any prefetch file that was created over two weeks ago which eventually will be any application you have installed. I've stated clearly with testable results as to why no PF file should be removed for any installed application. If you don't understand any of this then tell me where and I will explain further.

Oh and it is NOT nanoseconds. Anyone with Prefetching properly enabled can test this. Prefetching has to have been running and the application started at least three times, the defragmenter also has had to have been run to layout the associated files. I timed Avant Browser and it took 6-7 seconds to load. I then deleted the Avant Browser Prefetch file and cleared my RAM (important) then relaunched Avant Browser it took almost 12 seconds to load. So it is clearly NOT nanoseconds but seconds which is a significant difference. After it is run the Prefetcher creates the file back again. So subsequent launches are optimized again. But why woud you willfully kill application load times every two weeks? It makes no sense. It is like forced unoptimizing.

That is BS. I've timed this on numerous systems and the results are the same a 5-20 second improvement in application load times. Anyone who has had prefetching enabled properly can test this themselves.

Of course you system will run without it except it will run faster with it enabled. It can shave 5-20 seconds off an applications load time. Deleting the PF file for the applications cripples this optimization until the file is created again.

I advise you read how prefetching works. Anyone can test what I said, what are you afraid of? This is a serious issue and I will not drop it until it is corrected. Thus the warning on my site. CCleaner DOES NOT remove applications that were not used in two weeks it removes PF files with over a two week date from when they were created which is ridiculous and hurts application performance. Why would you want to slow you system down?

The prefetcher automatically cleans uninstalled applications and remaining files take up next to no space.. It shouldn't do this at all. It shouldn't remove any application that is still installed on your machine. It removed applications I use everyday. It is removing files based on the file date. It should only be removing applications that are no longer installed on your system which the prefetcher does automatically. The space saving argument is useless since you want a PF file for ANY application you have installed incase you run it again. It shouldn't even exist at all there is no reason to delete these files. No it UNoptimizes the system by deleting .PF files for applications you use everyday. Anyone can test this themselves. And this should have been tested to begin with.

You can simply test it no permanent damage is done.

No but I can confirm it happens with v1.0.6.

Just because CCleaner labels it "data" does not mean it is. Again please explain to me how Prefetching works. The fact that CCleaner labels it "Data" is clearly why it was incorrectly included as an option. NOTHING in the prefetch folder is Data. They are merely index files, one per application and boot items. Check this for yourself. You will see a file name per application you launch not various "Data" files. BTW it is the users choice to disable your CPU's cache in the BIOS too.

If you all really understood it then no one would be arguing with me. I'm serious I would like someone to explain to me how they "think" prefetching works. This will resolve the issue as I can show you what is misunderstood.

Ok I would like everyone who disagrees with me to explain to ME how prefetching works. This is the problem. You apparently do not understand how it works. We need to get this resolved so we can move on.

What does this have to do with mb deleted? Do you understand anything I have been saying?

No offense but try to understand how prefetching works.

It is NOT DATA. They are index files! Incase you START it!!! Windows will automatically remove ununistalled applications from the prefetch folder over time. CCleaner removes INSTALLED applications. It appears to just do some sort of date checking on the file, which is idiotic. It cleaned Avant Browser, Trillian and Thunderbird .PF files which are used every day on my computer. It is more like seconds, which add up. Nothing is CACHED Period. None of the files in the prefetch folder are loaded or CACHED!!!! They are used as references to load other files. No it does not, I have tested this on multiple computers, it should never delete a .PF file from an installed application. Why would you WANT to HURT performance?

The prefetcher only affects application load times and windows boot times. It will analize the applications launch and create the .PF file based on this information. If you look in the Prefetch folder you will see a .PF file for every application you launch. Subsequent launches reference this file and optimize the loading of the files the application needs to startup. When you delete the .PF file. Windows does not have this reference and has to launch the application less optimally the first time after deleting the file. Windows will then recreate the .PF file for subsequent application launches which will have the .PF file as a reference and the launch will be optimal again. This will be further improved after the Defragmenter is run and lays out the files in an even more optimal order. No data is stored in the Prefetch folder. The .PF files are index or database files. It is also not a cache. Think of it this way. You start Application A. Normally it loads A.dll then B.dll then C.dll in that order to start. The prefetcher determines it would be faster to load B.dll and C.dll at the same time before A.dll. This is what information is in the .PF file.

Proof Know what? I don't even know if you have it enabled properly to begin with. We are usually talking in seconds here but it can be more depending on your system state and the application. There are many factors to this and if you don't understand how it works then you will continue to believe cleaning out the folder does something. What do you think cleaning out the folder actually does BTW?

It shouldn't be there. Should Mr. G include every other useless tweak in CCleaner too? It has nothing to do with what people want. If people don't understand how something works they will request more useless features. Cleaning the prefetch folder is a myth, useless and reduces performance. You probably have prefetching disabled for all I know. None of which changes how prefetching works. If you think I am wrong, link to me the Microsoft Knowledgebase article or White paper that says otherwise.

First off those aren't recent blogs. Windows Prefetching hasn't changed since day one. And no it is not just nanoseconds it can be much, much greater then that. Shaving a few second off an application load or Windows boot is worth it. And since it does nothing but improve performance, disabling it or cleaning the folder is foolish. There is alot of misinformation floating around the internet, how prefetching works is one of them. But hey if you want to reduce your system performance feel free. None of this changes the fact that this should not be in CCleaner. Cleaning the Prefetch folder has the same negative effect on performance that using Memory Optimizers does.

Prefetching works exactly like it says it does. After three application launches or reboots Windows will create a PF file for the application or boot item. This file is used to optimally load the application into RAM on application startup and to let the Disk Defragmenter optimize the files layout on the disk. Of course your system will work fine without it. But you can't say it doesn't do anything because the performance increase varies depending on the application and your current system state. It is something that requires some time to take effect (3 application launches and disk defragmenter being run).

How much time you loose can vary by the application. But this also effects boot time performance. Regardless cleaning the Prefetch folder manually has only one effect Reduced peformance. It does NOTHING to impove performance and reclaims next to no disk space since the PF files are so small. Not to mention Windows will simply recreate the PF files the next time you launch an applicaiton as it should. There is NO reason to clean this folder once you understand how Prefetching works.

I understand I just haven't heard anything.

No you don't understand Cleaning this folder HURTS performance. Windows will automatically clean it but based on uninstalled applications. This is a performance hurting setting since CCleaner targets used applications. You don't understand how it works that is why you think it needs to be cleaned.

Is this issue being addressed? A new version is released and still no resolution for this. Other "cleaning" programs will let you know your web browser is running. I see Firefox is still enabled by default and selecting it gives no warning.

Right and it will not delete PF files from applications you actually use like CCleaner does. Cleaning it hurts application load time and boot time performance. Any performance gains are placebo. Here is a link explaining it in more detail: http://www.edbott.com/weblog/archives/000743.html

I noticed CCleaner has an option to clean "Old Prefetch data". This is completely unnecessary and should be removed. Since cleaning the Prefetch folder actually hurts application load times. Windows will simply waste time recreating the Prefetch file after it is deleted the next time that application is launched. The reason? Because the file is SUPPOSED to be there. Once it is created it will improve load times and allow the defragmenter to optimize files necessary for the launch of that application. Windows Prefetching is NOT a cache. So cleaning it is irrelevant. I ran a test and it deleted all sorts of files I use everyday. Not good.