A couple of months ago I reinstalled OSX. Ever since then I’ve had this weird problem of my drives acting sluggish. I would select the drive in the sidebar of the finder, and it would take 4-8 seconds before the files and folders were listed. The same thing would happen in “Save” dialogue boxes. It was very annoying, and I thought there was something wrong with my fresh install, because my previous system didn’t do that.
I totally forgot about this little checkbox in the Energy Saver system preference. When checked, it put’s your drives to sleep whenever possible. In my case it was doing it a lot with my 2nd internal drive, and my external Firewire drive. I was having to wait for them to wake up each time I tried to access them. I must have disabled it in my old system and forgot all about it.
If your drive seems sluggish, try turning this off. Go under the Apple and select “System Preferences”. Then select “Energy Saver”. The checkbox is at the bottom of the window.