[mass55th]

I use Macs, and hadn’t heard of Lightroom. Is this a program that came on your Apple computer, or is it something you purchased and installed yourself? A search shows Lightroom is an Adobe Photoshop program. You might want to contact them if you can’t find an answer to the beachball problem. Anytime the beachball comes up, it means the computer is thinking, or working. If it’s lasting a long time, you may need more RAM, especially if you run several programs at the same time.

[PIF]

Adobe Photoshop Lightroom 3 is a professional level image cataloging application. And it needs a LOT of RAM. Any bugs are Abobe’s not Apple's in this situation.

The larger the catalog one is working with, the more RAM needed. A high end graphics card also helps.

For large catalogs, either use the high-end iMac with the best card available and max RAM, or a MacPro also trickled out.

Look here
Optimize performance | Lightroom
http://kb2.adobe.com/cps/400/kb400808.html