I've been using Aperture since 1.0 and have a library of 40,000 + photos. After installing Aperture 3, the app is simply unusable at times. I can't run Safari + Aperture at the same time because together they use up 4GB of RAM, the amount I have on my MBP. Some people have suggested that I split my library into smaller ones and I'm willing to give it a try but I have a few questions before going ahead with it. The major advantages of having a single library and questions I have regarding them using separate libraries: - You can use smart folders to look through your entire body of work and identify the best photos, or all the photos taken at a specific location Q: I'm already willing to drop this advantage as I'm pretty sure smart folders in one library won't fetch photos from another. Am I correct? - You can back up all your work at once in one Vault Q: Will a vault back up all your libraries or just the one you presently have open? - You can sync photos from your library to your iPhone Q: Will iTunes enable you to choose to sync photos from different libraries or just one? I'm an event photographer and most of my photos are from nightclubs, although I do have studio work, some weddings and private parties. I'll split those up into different libraries and hope they make a difference. An additional question: When I create a new library for a certain folder of projects, will that folder be moved to the new library or simply copied? If the latter, is it safe for me to delete the original folder once the new library is made?