Hi there, I was asked why a 2009 iMac (3,06GHz C2D with 4GB RAM) would be somewhat slow with Mavericks installed on it. After a quick look at the Activity Monitor, the hard drive is far from full with about 40% free space, and RAM wasn't overloaded, nor was swap memory. From what the guy said, he upgraded it from Snow Leopard to Mavericks, and my not-so-educated guess was the Mac simply didn't like that upgrade, and the hard drive may be slowing things down. It is used in a small, mixed-OS office, implying MS Office, Kaspersky antivirus, financial files, etc. I am a bit at a loss trying to understand why it's sluggish. The guy wants to replace it if needed, but would like to try a clean install first. In my opinion this shouldn't be necessary. What are your ideas about this machine?