- Computer: Late 2013 27-inch iMac
- OS: Windows 10 Home through Bootcamp (upgraded from Windows 7 Home Premium)
- Processor: 3.5GHz quad-core Intel Core i7 (Turbo Boost up to 3.9GHz)
- Display: 27-inch 2560 x 1440, external display running at 1920 x 1080
- Memory: 16GB (two 8GB) of 1600MHz DDR3
- Graphics: NVIDIA GeForce GTX 780M with 4GB of GDDR5 - Driver Version: 364.72
- Broken: 2.77 abf6f08 (affects other versions though - see below)
- Worked: N/A
Short description of error
When using Blender through Boot Camp Windows 10 with an external monitor (Mini Display Port-to-HDMI Adapter), Blender exhibits serious UI lag. The only workaround I've been able to find is to unplug the external monitor from the computer. No other OpenGL applications seem to be affected, and there are no problems running Blender under OS X (10.11.4 to be exact). Here is a link describing a similar issue dating back to May 2015, which would be Blender version 2.74, or possibly lower.
Exact steps for others to reproduce the error
Run Windows through Boot Camp with an external monitor attached. Bug is independent of any specific .blend file (it occurs by simply launching Blender).