What makes the initial download of the blockchain so slow? If you download a bootstrap copy of the blockchain through torrents, it will be faster than getting that same data through the Bitcoin network. 

Ofcourse the BitTorrent protocol is more optimized for bulk data transfer, but is there any other reason for the huge difference in bandwidth? Is it artificially limited in the client right now, or by design?
I found this post by Jeff Garzik (one of the developers):


  Initial blockchain download occurs from one peer at a time.  If that
  peer is slow, then your entire blockchain download is slow.
  Yes, it's stupid and yes it needs fixing (patches welcome).