I've got around 90 Gig of data to transfer from an external hard drive to another external hard drive. I find it takes enormous amount of time to do so. I was hoping to get your help and perhaps provide a quick resolution to this?
If your external drives are USB 2.0 drives, the transfer is slow because the interface is slow. You could
1) Buy USB 3.0 external drives.
2) Crack the cases open and put the drives on your SATA ports.
I personally use option 2. I don't have external USB drives, I have ten SATA drives that I keep in a well-protected case and insert into these bays: http://kingwin.com/products/cate/mobile/racks/kf_1000_b... . It makes life really simple: When I want to use an external drive, I just hot-plug it into one of these. I have two, so copying between drives always takes place at the drive's native speed.
If you go this route, I can't emphasize the importance of careful disk handling enough. My drives are kept in a hard-shell case lined with thick anti-static foam with separate cutouts for each drive. Bare drives are (somewhat) more fragile than drives in external enclosures.