Hey John, Well I can't speak for Apple on why iPhoto bogs down after a gig or two of photos. I don't know why. But from experience, I know that it does. (And I also know that managing images is a lot different than handling text.)
You could use FileMaker as your photo database. I've seen them, and they're cool. But, I like the output features of iPhoto that I can't get from other systems.
What I'm trying to do here is show folks how they can use iPhoto, if they choose to, and still manage lots of pictures. And there are a couple upsides to the method I outlined in the article.
For one, you regularly archive on to optical media. I think it's safe to say that many of us don't back up out stuff as often as we should, and the results of not doing so can be disasterous.
Second, if you're a PowerBook user, such as myself, your hard drive probably tops out at 60 gigs. Regardless of any iPhoto performance issues, laptop users need to have a flexible system for backing up and retrieving data while on the go because hard drives fill up fast. This is especially true for photographers.
By taking along a handful of DVDs, you can provide hard drive relief and still quickly access your image libraries.
All of that being said, some people won't be satisfied with iPhoto until it can handle more pictures. No argument from me. That's the beauty of technology: there's always an alternative. I'm not trying to convince anyone to use iPhoto. But for me personally, the many benefits of this application outweigh the limited library size.
Thanks for reading!