Anyone familiar with Ghost corporate edition?

[SarcasticDwarf]

I am working a job where we are using Ghost 8.0 Corporate. Here's the scenerio using Ghostcast:

Note that each session is about 6gb and mode is unicast.

laptop 1:
15 images on session 1 - takes 3.25 hours
2 images on session 2 - takes 18 minutes

laptop 2:
15 images on session 1 - takes 3.5 hours
4 images on session 2 - takes 30 minutes


Now here's the question, what is causing ths speed to be so much faster/slower, seemingly depending on the number of systems being restored in each session? It isn't the network because there is so much of difference in speed even though they are running at the same time.