I'm a little surprised to hear you're having such slow speeds, as our content delivery network has a hub in Miami.
In general we recommend downloading as little scenery as possible at first so you can get flying as fast as possible. You can add more scenery at any time.
We did migrate our servers over the weekend, so it could also be a temporary slow down due to the change. If you haven't committed too much time, I might recommend canceling that one and trying again