Several orders of magnitude (and at least one computer) ago, I once had to upload a CDís worth of (public-domain) content. We started out figuring it was simpler for the content creator to burn the stuff onto a CD and mail it to me from Australia, but eventually it turned out it had to be uploaded anyway. It took eleven and a half hours, during which time the computer was pretty much out of commission.
I was bemused to note that the working directory for one of my in-preparation ebooks is 42.7 GB, or roughly 20,000 times as big as the hard drive on my first computer. File under: Things That Make You Feel Old.
I use (Mac) software for cloning and have found that is works MUCH faster and with less heat overhead if I turn off connections and antivirus/security software during the work. Imagine the extra effort to check/validate each byte before writing.