I experienced the same issues from the very moment I upgraded to version 8.1.6, which lead me to immediately revert back to previous version which runs perfectly. So for those having issues with NT8, have you tried reverting back to version 8.1.5.2?
And on that note, I will remain on version 8.1.5.2 until they publish the first patch for the train-wreck they created in 8.1.6. But even then, I will be watching everything under a microscope. And at the very first signs of any trouble I will immediately revert back to 8.1.5.2.
Hope that helps! Good luck!