Have you recently imported a large number of images that still need the generation of previews? That will take some time.
You can prevent Aperture from creating previews at launch, by holding down the "Shift" key while you are launching Aperture. That will defer the preview generation, but is only a temporary solution.
Do you want high resolution previews of your images? That is recommended, but will take some time to render. If you do not want previews, disable the generation of previews in the "Previews" preferences pane, also for each project by selecting it in the "Projects" section of the Library Inspector. The "Mantain Previews for Project" option is hidden behind the cogwheel in the upper right corner of the panel.
Sometimes the generation of previews will hang, if you have a corruption of the library or imported an image or video that cannot be processed.
To repair your Aperture Library, see:
To check for images, that cannot be processed, see this thread:
Thanks for that. You've reminded me to disable previews. What I've done is realised that having high quality previews added about 60 GB to the size of my library. (60k+ images) I have OS X, Aperture and the library on an SSD PCI card for speed and had previously had Aperture generate previews for new projects, Sharing wth iLife to never, Preview size to match monitor size (1920x1920) and quality to 0, to cut down the size of my previews and thumbnails to ensure that my library size was minimised as the SSD is only 256 GB. The library is referenced rather than managed and files are on a seperate drive in the Mac Pro.
With an 8 core 2.26 GHz machine and Radeon video card I'm quite happy to accept the hit on calling up the original file as the time to wait for the file to load using a high quality preview isn't much different to using a low quality preview.
Yesterday I decided to delete & rebuild the Previews and thumbnails & left the system overnight to do its work rebuilding everything. Closing and reopening Aperture after it completed its job just started rebuilding previews & thumbnails again and again. Opening the library package reveals originals and thumbnails are still there. I'm not sure why this goes into this repeated loop.
I've decided to export the projects I have into a new library to see what happens.
Closing and reopening Aperture after it completed its job just started rebuilding previews & thumbnails again and again
If all previews have been generated, and you still see frequent processing of previews, there may be two reasons:
- Your Preferences settings do not take, because the preferences file in the user library is corrupted.
- You may have imported a corrupted image file or video, for that the generation of previews will never succeed.
The first can be fixed by removing the Aperture preferences apple.com.Aperture.plist from your user library, see the Aperture 3: Troubleshooting Basics on how to do this.
The second requires to search your last import, and to try to generate previews manually for subsets of these images, to find the one, for which the generation of previews will hang.