The only solution for me was: Unpair iPhone from Xcode (in Devices & Simulators) Unplug iPhone Switch OFF and keep OFF the Watch Plug iPhone and Pair again with Xcode This is a really bad issue. In order to get some work done, you have to switch off your AppleWatch???? Apple??? TF?

I have a macPro Late 2012 with 12-Core Xeon, 64GB RAM, Dual AMD FirePro D700 with 6GB each, and have the same problems. After booting up, the graphics is ok for about 30 Minutes or so. But the longer I use it, the slower and more sluggish everything gets. Any window animation, scrolling through menus, they all are extremely sluggish. macOS 10.0.1 (final; not beta). I hope this gets fixed soon, otherwise it is a nightmare.. And yes, I have tried everything, including resetting PRAM/VRAM and SCM.