Vista slows down tremendously when dealing with zip files containing many
files. With a 375 MB zip file containing 80,000 files I found that Vista
would go near 100% CPU use and stay there for half an hour when I created
such a file or moved it to a flash drive. This was a big problem because I
couldn't safely remove the flash drive until the transfer was done and Vista
slowed to a crawl.
I found a fix (
http://www.annoyances.org/exec/show/article03-202) that stops
Vista from looking inside zip files. It completely fixed the problem, and
also stopped other less severe times in which Vista slowed down.
If you use zip files, this is a crucial tweak. You need to add a third
party program for zipping / unzipping, but Vista's built in zipping /
unzipping is so slow that you probably use a third party program anyway if
you have big zip files.