I can duplicate the issue with Excel. NVDA is ultra sluggish in Excel. I type a value into a cell and then hit enter or the right arrow and NVDA appears to lock up. There is no speech. I have to wait 2 to 3 minutes for speech to be restored. I can then type another value and then the process repeats. I was able to navigate the back stage view without problems. I am using Windows version 1703 (OS Build 15063.296)
I am running office 2016 and have the office 365 subscription.