You seem to be having the "Hamachi bug" where having another active virtual network adapter enabled is causing asset loading to become extremely slow in the Unity engine. This is known and we are working with Unity to find a suitable fix for a future patch. In the mean time, go to your Network Adapters and disable any that are being used for virtual networks (Hamachi, etc.).
Thanks,
Roby
Thanks for the reply, this solved the problem! I turned it off a while ago, but it was turned on after I rebooted.