How does SCCM download the packages in the CCMCACHE area?

Question

What is the default behavior for SCCM downloading packages into the SCCM ccmcache area?
Here's what we're seeing when installing a package on a "clean" test machine:
A subfolder is created in the ccmcache area (typically named 1, 2, 3, ... a, b, c, etc.)
A temp subfolder is created in the ccmcache area as well. Named the same as the package cache folder created above with .tmp added.  Now I have a, and a.tmp folders for example.
The package starts to download into the "a" subfolder, but not how I would expect.
  First, all of the folder structure in the package is created in the ccmcache area.  The foldernames are correct. There are no files yet.  This can take 10-15 minutes.  All I have is a directory structure.
  Next filenames start showing up in the subfolders. However, they are all zero sized files, and they have temp filenames, not the real filenames. Again this takes 10-15 minutes.
  Next the zero sized files begin to download content. This is the actual downloading of the files. They still have temp filenames. (The package I'm working with is 4.3 Gig).
  After the file content has completed the download, all of the temp filenames are renamed to their original file names. Again this takes about 10-15 minutes.
  After all this, the software installation actually starts.  The SW installs in 17-19 minutes.
Is this the expected behavior? Why not just DL everything in a typical method like you'd see with a copy, xcopy, or robocopy type command?
Any help is away appreciated.
Background:
I only work on creating the SW packages, not on administration of the SCCM tool itself, so I'm not familiar with how the SCCM delivery method is actually setup.
SCCM 2012
Working on a development server, so the package is not available to all yet.
Test machine is a typcial Win7 x64 VM.
The package is primarily a drag and drop application.  4.3 Gig in size.
The files in the package are not compressed.
Virus scanning is disabled for the ccmcache directory.
I just switched to packaging w/ the SCCM tool, so please forgive my ignorance with the tool at this time.

Answer 1

The major reason for asking is that the download of the actual file content doesn't start until 30 minutes have passed.  30 minutes to create a directory structure with zero size tmp files is an excessive amount of time.  Once the files have been
downloaded, it takes another 15 minutes to rename the files.  Again, this is an excessive amount of time.
I almost think it would be faster to exclude the files altogether from the package, and just have the package include a simple install script that robocopies the files from the network.  I'd just need to test whether the network copy would be slower
than the additional 45 minutes the BITS download is taking.
I'm just one of the packaging folks, so I'm not familiar with how many distribution servers we have or where they're located.  I package engineering tools which can be in the 4 to 12+ Gig range.
I'm done testing the package, so for now, we'll just tell the users to install the software right before they leave for the day; it'll be there when they get in the next day.
Thank you for your replies.
Regards,
Dan