Filling your Mac's Hard Drive - Don't!

Mac OS X needs at least 10% of the startup drive's capacity for temporary system use. Once you fill your hard drive over 90%, the file system can get extremely slow.

The cure is to delete as much as you can to bring the free space back up above 10%. You will be pleasantly surprised at how much more responsive the Mac will get. Deciding what to delete is a challenge, though. I have used a utility called Grand Perspective (a free download) to examine the drive - it shows you graphically where your largest files and folders are. There are several other such utilities. They display the contents of your drive in a colorful diagram that makes it easy to tell which files are using the most space.