The .NET frameworks will not be causing any issues as I'm always on the most up to date with my install.
What would have been an idea was to check your network drivers and network adapter settings (from Device Manager) on the working version, then see what they had changed to on the new version. Has the network adapter driver been updated? Have some of the properties changed, for example energy saving settings turned on when they were off before. It would also be worth monitoring the network when the computer should be idle to see if its busy moving a lot of traffic, is it trying to share the update to other computers on your network or the whole world. Also after updates Windows can take hours or days sometimes in optimising new code. What is the CPU showing for usage? Is something stuck taking up a lot of resources on the CPU?