For about 2 1/2 years, I have had MacBook Pro running Mac OS 10.4.11 with a 2.2 GHz Intel Core 2 Duo processor and 1 GB 667 MHz DDR2 SDRAM. Over time, it seemed liked my MacBook was struggling more and more with running multiple applications so I uninstalled and turned off as many unnecessary programs as possible; including turning off all dashboard widgets.
Most consistently, I would get a spinning ball of death every time I opened iPhoto while also running Firefox; which made it really difficult to blog about hiking trails. I thought the problem was due to having a large number of photos and videos for iPhoto to manage so I tinkered with its settings to no avail. I was unable to find anything in the Apple forums to suggest that my problem was caused by iPhoto. In addition, my Activity Monitor reported iPhoto as using a normal amount of memory. As it turns out, the solution was simply to install an additional 2 GB of memory ($100); putting my total to 3 GB. My MacBook has been running smooth ever since; even with multiple programs open at once: Firefox, iPhoto, Safari, iTunes, and Seashore (image editing software).