I've been sorting and transfering files between my old externals into a new 4TB I bought and because the older HDDs were USB2, the whole process takes several nights. Files are transferred from old HDD to Mini's HDD, while files already in the Mini's HDD are transferred into the new usb3 HDD. The entire process takes hours, longest one has been estimated at 15 hours. I've disabled sleep, display is set to go off after 15 minutes. After the whole process, I return to 'wake' the system and it'll spend a good 5~10 minutes just lagging, kinda like how vista/win7 is like after waking from sleep. A simple process like opening a Finder window takes a few minutes to load. Is this some kind of power-saving feature/bug? No SSDs installed, spinning platters only.