That, to me, feels like it's a problem with your computer, rather than your internet speed. Desktop is usually space on your system disc, so the delay would seem to be in copying the files from one area of your disc to another. Is your C drive getting full? Do you have any other discs attached that you can copy the data to? That way you could attach the copies to the email and see it that's any quicker. By "other discs" I mean completely separate pieces of hardware, not partitions on the same disc. If your system disc is a mechical disc as opposed to an SSD, it could mean that it need defragging. Some systems defrag automatically nowadays but, if yours doesn't, a badly fragmented disc will slow down reading and writing to it.