Why is it so slow when i'm downloading the norton client, it takes too long to download it

The last three times after I formatted my pc and I tried to download the Norton security client from the Norton account site, the first 50% of the total client size downloads very fast, but after that, it gets very very slow..i have a 35 Mbps connection, and it makes no sense that it takes that long to download half the client.

Why does it happen?