My iMac has suddenly become terribly slow (i3, 3.06, 12GB RAM). Not sure if my recent upgrade to Mountain Lion has anything to do with it, but I'm suspicious. I've checked everything else possible and am looking for solutions. As a photographer I utilize my iMac and external drives as an image database. File transfer among drives is moving at a snail's pace. Recently had to connect some drives via USB2 rather than firewire daisy chain, tho had some previously without a noticeable problem. I would be happy to get back to the transfer speed I had previously. Any reasonable suggestions would be welcome.