Aperture has suddenly become VERY slow to open my library. Is the the “opening…” dialog for a little while, then a blank Aperture window for a while more, and then finally the photos in my library.
Repaired the library
Rebuilt the library
Deleted Aperture's preferences
I also moved a copy of the library to another computer where it opens quickly.
What else can I try?
My next step might have to be to reinstall the Aperture application.