My father has an alluminum iMac that is 5 years old. He's had no issues with it up until last week. The iMac started slowing to a dead crawl. Since I'm the technical support in the family, I was helping him to narrow down the issue. I live 2000 miles from him so there were a few limitations on what I could do but we worked it out. Anyway, we did the standard stuff. Booted into safe mode, fixing permissions, the works. It helped a little but the main issue was that the machine was the apparent victim of the Mavericks memory leak. Basically, the 4GB of RAM was filling up and there was 17GB of swap. Really bad. After doing what I could for him, he decided to take the iMac to the nearest Apple store. It was interesting what they found. Apparently an old HP printer driver that was not compatible with Mavericks was still active causing major issues with memory. The genius deleted the driver along with a few other files and Voila! The iMac was back up and running at full speed. On top of that, they did not charge for the service even though the iMac was way out of warranty. Great service! So I guess the moral of the story is that for those with crawling iMacs using Mavericks, be sure to check your drivers or any software that you don't need or should not be there. Probably a bit easier than nuking the entire machine and starting over.