Recently installed a licensed copy of Office 2010 on my W10 PC, running at 4.1 GHz. Word 2010 takes 17 seconds to open. Isn't this too slow? My old copy of Word '03 opened very quickly. The other components of Office 2010, open very quickly.
This Office 2010 was lying around for years, and I had forgotten I had it, till I cleaned up my desk. It is fully activated, and otherwise, works fine.
I'm not a Word fan but that is real slow. I would try the repair function built in and be sure you have all the updates. My LibreOffice opens the choice screen instantaneously and the Writer in about a second and a quarter.