it only download the maps once (unless theres an update server side) the only thing you can do is just wait till it finishes, it once they are on your machine it wont keep redownloading them
It is normally best just to let it download until it is finished...somethimes it may take a while, up to several minutes, before it starts to move again. If you think that it has been downloading for far too long then you can try just hitting the stop burtton and then hitting start again and this will sometimes get things moving quickly again. If you are getting alot of mesh errors/problems then I would suggest deleting everything in your mesh folder (or just create a new folder) and letting it download again from scratch. Remember, everything takes a lot longer if you are visiting a zone for the first time. After the mesh has downloaded and is on your harddrive the program takes very little time to load the mesh for use.