I just upgraded to the current Mini (2.5 ghz i5) from my late 2009 Mini, and the new was is achingly slow. It is quite slower than my old one. Clicking on finder windows causes a delay (3-8 seconds), and I spend a whole bunch of time looking at a spinning beach ball. I'm running the current version of Mavericks, have 4 GB RAM, and transferred my files using migration assistant. I have repaired permissions, but haven't done much troubleshooting. My old Mini had 8 GB RAM, so I'm thinking about upgrading this one to 8 as well, but I don't think it is RAM that's causing things to be so laggy. Any ideas?