So, you are agreeing it takes a longer period of time, in minutes and seconds, to completely copy a larger file than it does a smaller file from HDD "A" to HDD "B" within the same computer? The "other factors" are irrelevant ... make no difference. They apply to all copy processes on the computer so they have the same effect on every copying processes.
So your computer is not up to the task as I suggested as an explanation in my first post when I said, "It would be helpful to know more of your system specs. You may simply have a low end machine with minimal specs."
Sorry, I don't agree with you because you're talking about a much different size of 2 files while I was talking about different files which finally had TOGETHER the same size as the 1 big file! The transfer of small files with the combines size of an huge file will need longer time. Unfortunately I'm in hospital and didn't have my normal computer at hand, just my Laptop and could not do such sample transfer while capturing the time. Do it on your own and the same computer and you'll see the difference. Alste the type of files are relevant!