I have an external usb dvd drive and an internal blu-ray drive. I use both at the same time for ripping movies to My Book 3TB external hard drive. I've noticed that the external dvd drive is considerably slower than the blu-ray drive. Any idea if the cause is because the dvd drive is usb connection instead of internal drive? If I replaced it with an internal dvd drive do you think it would be faster? I don't know the R/W rates of the two drives.