It seemed to slow down for me too, though not to the extent it did for you. It's maybe 25% to 33% slower. For those who have a "slower" internet connection compared to other users, the problem seems to be magnified.
But keep in mind that Big Fish is putting out more bloated games -- over a GB, and larger even than some adventure games. Those are just going to take a while to download -- especially if Big Fish is having a sale and is busier than usual.
Sometimes you just get a worse connection than usual, and it helps to cancel the download and try again.