I see that you installed Sierra. If your findings were with that pre-release quality software, then – particularly for discussion of CPU usage – it may be better to shift to the the given sub-forum (and give feedback to Apple).
I installed Sierra on a separate partition (clean install). My main working environment is El Cap and experience the very high CPU usages. It seems to be a fairly common issue as googling Office 2016 CPU brings up a mountain of threads.