I am having the same problem using an R9 390...
Do not count on Windows to be fully up to date when it comes to device drivers
Go to the vendor site to be sure you have an updated driver for your graphic adapter
•ATI Driver Autodetect http://support.amd.com/en-us/download/auto-detect-tool
There are also intermittent reports that the newest driver is not always the best driver due to driver bugs or compatibility issues, so you MAY need to try an earlier driver version
I understand that you have updated your Windows and now your Lightroom app is not performing well.
I would suggest you update your CC app because it might be due to version incompatibility.
You may also uninstall and reinstall the app from your CC Desktop app Download Adobe Creative Cloud apps | Free Adobe Creative Cloud trial
I called Abode Support and got some help with this. It seems to be the graphics card (again, I am using an R9 390). You can go into Lightroom and follow the path Edit->Preferences->Performance. In this tab, you can toggle whether or not Camera Raw uses your graphics card. Unchecking this box solved the problem for me.