Justin Blanton | From iPhoto to iView MediaPro:

iPhoto is a good starter app - if you've only got a few photos, and just want a convenient way to store and browse them,. it works fine. But it's limited - once your image archive gets into the 'a few thousand photos' range, it gets very slow, and managing your photos well becomes more of a chore.

If iPhoto's limitations are getting you down, you're probably on the market for a better way of managing your photos.

aperture looks like it may be what you're looking for, but you could also look at alternatives (which also happen to be cheaper) - like iView Media. Justin's post on migrating from iPhoto to iView Media Pro might just be a good place to start. Even better, there's a free download trial of iView Media as well.