|This gets a bit technical. If you want to jump straight
to the solution.. jump down to the blue
There is a little known secret to Windows.. if you have too many files in a single folder (say >20k files), windows goes to a crawl because it has to power-search the directory to be able to find the one file you're looking for. As you put more and more files in a folder, windows keeps increasing the length (and the file size) of the folder. Once you get over about 5,000 files in a single folder, windows will really start to crawl because it's a simple list that has to be power searched.
The problem: When you erase files in a folder, the space for the file data is released, but the directory entries themselves are only tagged as 'unused'.
Unfortunately, one of the most common folders to experience this is your Temporary Internet Files, and today that one folder happens to be central to a lot of activities you perform. Too many directory entries in this folder will cause Windows to feel sluggish.
Just using the IE option to 'clear cache' or 'delete Temporary Internet Files" does NOT fix the problem. That frees the data space used by the files, but the folder as a file itself is never reduced in size. Even your plain vanilla defrag does not 'compact' the contents of folders. What's sad is that IE7 actually made an attempt at fixing the problem, but there are several other applications (like ms-office) with internet enabled options that have managed to actually make the problem worse.
Unfortunately, the fix is trivial, but Windows has done a good job of making it difficult. The fix: Periodically delete your folder named "Temporary Internet Files" (about once a month is usually good).
The problem: On your pc if you browse to "c:\documents and settings\_username_\local settings\temporary internet files" - windows treats this as a special folder and it won't let you see the sub-folders underneath here. Instead, they flatten the folder to show you all the files in any sub-folder, and they throw in your 'cookies' for good measure, even though the cookies are stored elsewhere on the disk. And, while you are logged on, windows has files open in this folder, so you can never delete the folder.
The simplest way to deal with the problem is to log into your pc as 'administrator' (not your normal login) and then find "c:\documents and settings\_username_\local settings\temporary internet files" and delete the entire folder. When you log back on with your normal username, windows will create it anew and you'll have a speedy computer. It's a good idea to do the same to "c:\documents and settings\_username_\local settings\temp" while you're in there.
I've seen this fix "slow computer" syndrome over and over.