Aren't some of those files intended to help my computer run faster? Should they really be deleted?

Cookies, copies of web pages and other bits of information are stored on your computer as you surf the web. Your browser often can use this information when you next visit the site to make it appear to access the page(s) more quickly. This is because some of the information may be, in fact, retrieved from your computer's hard disk instead of having to download it again from the actual web site.

However, the speed gained is not that much unless you are accessing high graphic web pages, and you tend to visit the same pages over and over again. When you visit a page, your browser doesn't know whether you'll be revisiting it again any time soon. As a result, it caches the information anyway - just in case. The consequence of this is that your hard disk rapidly fills up with "junk" data from sites that you visit once then never visit again - like when you mistype a URL or click on an invalid link from a search engine. Over a period of time this can lead to a sluggish system and shortage of disk space.

There also are some serious privacy issues and concerns because many internet sites store "cookies" that can remember where you have been or how long you have been in a certain area. Your web browser also stores on your machine a history of all the sites that you visit as you surf the web. In some cases, these may have been accumulated ever since you began using your computer/browser. This information alone can reveal a great deal of information to others about your use of the Internet. Additionally, these files can consume large amounts of your hard drive space without you knowing it!

So, these files can be used to improve the apparent performance of your computer on the Internet. However, it is a good idea to flush - i.e. delete - these files periodically to avoid excess overhead and clutter. For sites you visit frequently, the necessary files will be replaced on your next visit. For those sites you never visit again - and even those that have changed significantly since your last visit - you gain extra disk space and improved performance by deleting these files.

Not only do different browsers store these temporary files in different locations, but even different versions of the same browser may use different locations to store the files.

Tip: After running CleanUp!, you may also want to run a disk defragmentation utility. This will ensure that you obtain the best performance from your machine.

Some versions of Windows (in fact, all except Windows NT, I think) come with a disk defragmenter one called defrag. To find this look for Disk Defragmenter under Start, Programs, Accessories and possibly System Tools (the exact location depends on which versions of Windows you have installed).