Pretty short story, I just wondered what was at play here. I have a windows 7 box with NTFS on it. I don't have any application that can open/read/anything .dmg on that PC. I have a 7GB CD image in .DMG format. I tried to copy it to my external and it was moving along at about 1-3 Mb/sec (according to the advanced file copy dialog.) I stopped the copy and changed the extension from .DMG to .JPG and copied the file. It was moving along at 30-50 Mb/sec. The target and source are both NTFS.
What is at play here?
Also, I'm not concerned about my low transfer speeds as a whole, I was using an old external hard drive over USB 1.1, but I'm more wondering why transferring a .JPG is over an order of magnitude faster.
I also tried this multiple times. Every time, the speeds were roughly the same.