When I installed Windows XP, I noticed it could treat .zip files as directories. This is nifty at first, but slows things down, especially if you have a directory filled with .zip files (like, I don’t know, your Downloads directory???). It has to decompress them all internally, throttling your CPU and blocking UI events (like switching directories to stop the slowdown). In contrast, if you try to actually decompress a zip file using the built-in wizard, it takes f o r e v e r. I have a hunch they’re making it a low-priority background process, so you can do other things while it’s decompressing. Problem is, 99% of the time, I just want to work with the files it’s decompressing! I didn’t see an option to speed it up, although I haven’t looked very hard, because it should be easy enough to find. Conclusion: Microsoft is stupid.
     I found a nifty utility called 7-zip that has made my life much easier. It decompresses things right away, using a context menu. Just right click on the file in Windows Explorer, and choose Extract Here (or Extract Files…). It works right away, no waiting, and handles a multitude of file types (originally 7 different kinds, hence the name). This includes .rar files and mulit-part files (where the files have sequential suffixes, .1, .2, …, .n), using the same, easy interface. It’s completely free, open source software. You don’t even have to deal with WinZip’s nagware.