can i delete the data in the prefetch folder ?

To the contrary, it will actually take longer to do certain tasks.  It willl NOT increase performance in any way.  It should not be deleted.  See this Microsoft article:http://windows.microsoft.com/en-US/windows-vista/What-is-the-prefetch-folder.

Perhaps some normal maintenance is in order to increase performance and increase space.  Review the following:

A great many things influence the speed and performance and available space of your system - mostly the existence of various files and what's loaded on the system.  There are ways to handle this in Vista (and you should follow all the suggestions) - and of course the amount and type of RAM and the speed of your processor and motherboard (but I'm just going to discuss software solutions here - you can go to your computer vendor/manufacturer for hardware solutions if any are available (I, for example, am maxed out at 2GB RAM by my motherboard and there is no better motherboard available for my model of laptop but if your system can handle it, Vista 32-bit can use up to 4GB of RAM and the 64-bit verion can use even more).

One very important thing to begin – do NOT use any Registry Cleaner or Registry Booster software no matter what it says (scans will tell you you have thousands of errors just to get you to download and install the program or worse, buy it) or where you got it (even safe sites sell these products but they are not worth the headaches they can cause). Most do nothing of value and some can do great harm (to the point where you need to do a clean install to fix the problem – and that’s not even counting the fact that many such programs are actually malware in disguise). Vista keeps the registry clean on its own quite well and doesn’t need any help.

To improve your speed, do Disk Cleanup using: http://www.vistax64.com/tutorials/76073-disk-cleanup.html. Delete as much as you feel comfortable doing – nothing deleted there will harm your system in any way.

Also do an Optimization: http://windows.microsoft.com/en-US/windows-vista/Optimize-Windows-Vista-for-better-performance. Do all of the options.

Go to Start / Search options and type in msconfig and enter and then double click on the program icon that appears.  Go to the startup tab and uncheck any program that you don't need starting at startup.  That will probably be the majority of items there - if not most of them (some are needed like the AV program and Windows Defender but most are there to make opening the source programs faster and make you think they're more efficient).  This will free up a lot of RAM and help a lot in making your system faster (though perhaps not so much that you'll be able to notice the difference - but maybe depending on how much unnecessary stuff is loading at startup). When I did this on my system I removed over 90% of the entries and suffered no ill effects – to the contrary, I noticed startup was quicker, reponse times when working were better and I could open more programs at the same time and still have no problems, and shutdown was also faster.  Better still, download Autoruns http://technet.microsoft.com/en-us/sysinternals/bb963902.aspx which is much superior to msconfig and click on the Everything tab and do what was suggested above.

You can accomplish some of these tasks (and more that aren't entirely related) by usinghttp://onecare.live.com/site/en-us/default.htm (which also searches for malware).  I do this on a monthly basis just as a part of normal maintenance and I suggest you do the same (except for the registry cleaner – no not even Microsoft’s own product is entirely safe and the product has been removed from the paying marked for reasons unknown though it’s still available here for now but probably not for long).  Make sure you select a full scan - it will take a few hours (mine can take around 5-6) but can work in the background so start it when it has enough time to complete.

You also want to have good AV and AS programs on your system (so no malware is operating in the background draining resources).  Windows Defender is a good AS program.  The new, free Microsoft Security Essentialshttp://www.microsoft.com/security\_essentials/default.aspx is an excellent AV/AM program that has one of the least impacts on system performance and resources according to reliable sources and it does the job very well.  If you're using MSE, you don't really need Defender (but you would with any other AV program).  I would also suggest downloading http://www.malwarebytes.org/mbam.php and running it monthly to catch anything that MSE/Defender might miss.

If you follow this advice and do it periodically (at least monthly) then I believe you will have as fast a machine as it is capable of going given the hardware.

Good luck and I hope this helps.

Lorien - MCSE/MCSA/Network+/A+ --- If this post helps to resolve your issue, please click the "Mark as Answer" or "Helpful" button at the top of this message. By marking a post as Answered, or Helpful you help others find the answer faster.

My Prefetch folder contains 237 files and a sub folder called ReadyBoot.  This would appear to contradict the information above.

While the marked answer is technically true, you will not gain speed, I take issue that it won't help your computer performance. I have found that emptying the prefetch folder (but leaving the layout.ini) will help with Windows stability and performance.

While the folder is "self-maintaining", in that programs that aren't usually used will eventually disappear from it, apparently the programming behind the prefetch folder is not smart enough to recognize that it needs to remove entries for programs that get updated. At least, that's my theory, because it seems that often the snippets in the prefetch folder actually make frequently run programs more flakey.

Here's my experience...

Frequently I'll have a user that starts experiencing really odd issues with a particular program. There was a time I thought the program might have gotten corrupted or something, so I'd repair or re-install the program. However, one time I noticed there were issues after a recent update of the anti-virus program. So I tried emptying the prefetch folder the next time there were issues, and VOILA everything started working correctly again! The only thing I had done was deleted the prefetch folder contents.

I found this in Windows XP, but it's continued to prove true with WIndows 7 and Windows 8. We haven't rolled out Windows 10 just yet, but I imagine that I'll have the same thing there. So about once every couple months, I clean out the prefetch folder (while leaving layout.ini for windows auto-defrag) to keep things running smoothly.

My prefetch folder has 144 files. Tuesday said max of 128??