Hey Golgenth,
apologies for the belated reply. We've been looking through all your information (thanks again for that, it's very complete and informative!) and haven't found an issue with your Engine setup.
Could you send us your pc specs (GPU, RAM, SSD/HDD) ? We'll try to setup a similar build (Windows 8.1 etc.) to see if we can find the issue that way.
Sincerely,
Kevin
