Computer Extremely Slow When Internet Disconnected

I've discovered an odd issue with my computer. When there is no internet connection, it goes extremely slow. Simple programs such as VLC and ACDSee took something like 10 seconds to open. These programs are also installed on an SSD which makes these figures even worse than they would normally seem. Anyway I figured it was an issue I could fix with a reboot, however when windows was starting up, at the point where the desktop would finally appear, black screen. I can ctrl+alt+del to open task manager and I could see that there were 6 processes open, and nothing else was continuing to load. Safe mode with networking suffered the same problems.

At some point I disconnect the computer from the router, intuition I guess, and viola! Everything starts loading fine within 10s of disconnecting it from the router. I restarted multiple times with it disconnected, connected, disconnecting after few mins of black screen to confirm that it was the issue, and it indeed is. Same thing happened with Safemode with networking. Disabling the NIC seems to fix the issue as well. And of course when the internet came back on, it works perfectly fine.