Generally, the moment photographers are most anxious to view their images is when theyre first importing them from the memory card to the computer. Apple rewrote the importing process in Aperture 3.3 to address this anxiety, and its especially impressive for Raw shooters.

The instant you initiate the importing process, Aperture grabs all of the embedded JPEGs and displays them. (Every Raw file contains an imbedded JPEG that is created by your camera. Aperture uses these to speed things up.) It then downloads the larger Raw data in background. This means you can start sorting and rating your images immediately.

To keep things running briskly, those embedded JPEGs remain your previews until you begin looking at larger versions of the photos in the viewer. At that point Aperture replaces the embedded JPEGs with its own high-quality previews.

This process is different from previous versions of Aperture that would churn away at building its own previews while you were trying to work on a particular file. Now you have more processor available for the work that you want to do in that instant.