If you have the iLife ’04 suite installed on your Mac, run Software Update. iPhoto has been updated to version 4.0.1, an upgrade that offers stability enhancements, faster importing, smoother image viewing, easier Rendezvous photo sharing and better thumbnail images.
To take advantage of the improved thumbnail images, you also have to upgrade your thumbnails, which Apple warns “may take a while, depending on the number of photos in your library.”
System requirements call for Mac OS X v.10.2.6 or later. If you’d rather download the update manually, you can do so through a download page on Apple’s support Web site.