You'll not have any trouble with most processes on any dual-core 2GHz Mac with 4 or more GB RAM. (With only 4 GB, you shouldn't run any other programs when Aperture in running.)
Sharing Previews is a no-no (but IME it is the single biggest bog-field in the app). Load time will go up. Faces may become slow. It will take A LONG TIME (days) for Aperture to finish all its initial internal processing. Search the forum for general suggestions on keeping Aperture running well.
I built up a test library of 250,000 images just to make sure. I was able to run this Library off of an external FW400 drive (the whole Library, not just the Masters) on a 2.3 GHZ dual-core laptop w. 4 GB RAM.
I have since put together a database of 350,000+ images. It runs fine. I'd say it runs "normal" on all machines, as long as operations are kept to 100 images or so. Relocating a quarter-million Masters will take some time. Moving 10,000 images into new Projects, or moving those Projects into new Albums, can take a few minutes (but under ten).
You should set aside a week for the import and all the processing. I strongly suggest turning Faces off until the Library is structured and working (you've made most major changes and you've not stumbled across any glitches). Then you can turn Faces on and let it run in the background for a few days. I suggest NEVER turning on "Share Previews". YMMV.
My experience w. a 350,000 image Library leads me to believe that it could handle 10x that. The breakdown of the work seems to have been well-engineered to fit the currently available pipelines. But -- the faster your machine, the faster Aperture will run. Tony Gay and I compared his PowerMac with my MacBookPro for some Aperture tasks -- his was twice as fast.
Message was edited by: Kirby Krieger
PS: (Add to my previous message) Just a couple of hints:
- Never force-quit Aperture. If Aperture is processing, it's doing something it needs to do. Force-quitting, IME, always makes things worse. Let it finish, in its own time, all of its tasks. Since I stopped force-quitting Aperture (and since the last "fixing 3.x" updates) my Libraries have been rock solid.
- Carefully read the User Manual page on Previews. Devise a Preview creation and deletion program that meets your needs.