Then there is something wrong with your Internet and not your consoles. To download 1GB on my PS3 or Xbox takes about 10-15 minutes which is approximately four to five times faster then the Wii U on the same connection.
Ok sure, is your connection the holy grail of connections? Like I said the Wii U has downloaded the large day one update and demos twice as fast as PS3/360.
Maybe because Nintendo Network doesn't have as much players yet as PSN or Xbox Live that could be the reason I get no lag, not sure.