My experience and troubleshooting the problem.
1st. After Summerset, I was crashing and stuttering. I found the problem for crashing. My system was over clocked and worked great since beta. I run a 1080 nividia GTX and a Intel 5820K Cpu overclocked. The crashing was a result of my OC with only using 2 cores most of the time. With the summerset update, my system was now running all cores. This increased the voltage and frequencies in the cores. I turned of the OC and the crashes ended. I knew I would have to redo my OC later.
This did not solve my Stuttering issues. They actual became so bad the game was unplayable.
2nd. I had to troubleshoot. ISP was not the issue. Been running great and my fps and latency were at 100 each. Next up was my drivers, video and all associated hardware. Everything was updated and working great. I proceeded to do the usual changes in the game, remove addons lower settings etc. Still no change. The next in line was my modem, which by the way is brand new. All checked out. Went next to my router. The router was working. I disconnected my router and ran directly to my modem with no change. Finally my last resort was my NIC card. I updated all my drivers if needed and with no success. However, I then disconnected my primary nic from the router and moved over to another NIC card. This WORKED. I then connected back to my router and still no problems. The game is running smooth again. At this point my NIC card is the culprit, Y, I really dont' know. Just a part gone bad. I uninstalled the NIC and put it back and then reset it up but still with no luck. Bad is Bad.
I will keep an eye on my system, but so far so good. Just some things everyone else should look at. especially if you have been working great prior to summerset. I beleive the multicore is an issue in some systems. As for my Nic going bad, just bad timing.
I also flashed my BIOS with the latest driver and OC my CPU again. Running great and no crashes.
Hope this helps others. If i break again I will add notes. Feel free to add any other helpfull tips.