Hi,
Couple things. One is that in 3d mode the resolution of the texture (map) on the model increases, so you may see download tiles if the higher resolution tiles for your current tileset have not yet been downloaded yet. Check this by zooming in, in 2d mode. See if the tiles download, or are there.
I'm seeing fast download from open aerial (in my area, anyway - where are you looking?). Good downloads from color, and B/W seems to be down or not responding at the moment.
Hope that helps some....