MONDAY, September 7, 2020 – 12:47 AM
The story here is simple. Mozart wrote an overture for his opera. But there is a bit more to what you are hearing, because the real overture does not have an ending. It is meant to flow right into the 1st act of the opera. When you hear the overture in this form in an opera recording, it modulates to the key of F major and slows down.
Apparently it has a different ending as it is performed in concert, ending on a triumphant D major chord, and that’s what this version does.