OK think I have solved it…
This issue isn’t just on Unreal its across all apps on my machine… Basically you need to remove context menus (for NVIDIA and in my case Intel as well)
http://www.intowindows.com/fix-slow-desktop-right-click-in-windows-10/
(try this first)
if this doenst fix it then using CCLEANER - disable all the context menus via Tools options
Hope that helps some of you out there…
Dunk !!!