In trying to resolve an issue I had with MS Photo Editor responding slowly and generating network traffic, I discovered something I hadn't realized about networks.
See thread for reference: http://forums.techguy.org/t304166.html

My default printer is a network printer physically connected to another computer. The computer I was running MS Photo Editor on connects to the network wirelessly. As I was making changes to the picture, the application appears to have been attempting to render it for printing.

Once I installed a non-existent local printer using the same drivers as the network printer and set that as the default, the delay and the network traffic problem disappeared.