I just downloaded the game for the first time too; it appears to be updating game files; IE, downloading old game files that were either replaced during a game update, or game files you don't have on your system. And because this is your first time running it, I'm guessing, it's downloading every single game file you don't have, which is all of them. I doubt it'll take this long to launch the second time.
I think the only thing you can do is to wait for all the game files to download; don't stop it when it's in the middle of this, because I've learned that an unexpected quit during a download session will often make it start over from the beginning.
