I don't know what it is about it. When I was downloading the Family Guy movie, my BitTorrent client was running at 1 or, if i was lucky, 2 kbs. I downloaded and ran Azureus and the speed was scary fast.
Let's just put it this way: With BitTorrent, I'd be fortunate to top out at around 60 kbs. With Azureus, I just downloaded Plans by Death Cab in about five minutes. I average probably 150 kbs on Azureus, topping out around 215 every so often.