google is your friend….. same with wikipedia

All the answers below where pulled from searches off of google!

DHT – Distributed hash tables (DHTs) are a class of decentralized distributed systems that provide a lookup service similar to a hash table: (key, value) pairs are stored in the DHT, and any participating node can efficiently retrieve the value associated with a given key. Responsibility for maintaining the mapping from keys to values is distributed among the nodes, in such a way that a change in the set of participants causes a minimal amount of disruption. This allows DHTs to scale to extremely large numbers of nodes and to handle continual node arrivals, departures, and failures.

Local Peer Discovery – One of the features that I’ve been anxiously awaiting is the “Local Peer Discovery” feature in uTorrent 1.7x. Basically, it uses a multicast to discover bittorrent clients that are active on your local network. It can determine if they are seeding or leeching a torrent that you’re interested in. If it’s available on the network, it will try to use it as a peer, and download it at massive speeds.

Peer Exchange – Peer exchange (PEX) is a feature of the BitTorrent peer-to-peer protocol which, like trackers and DHT, can be utilized to gather peers. Using peer exchange, an existing peer is used to trade the information required to find and connect to additional peers. While it may improve (local) performance and robustness—e.g. if a tracker is slow or even down—heavy reliance on PEX can lead to the formation of groups of peers who tend to only share information with each other, which may yield slow propagation of data through the network, due to few peers sending information to those outside the group they are in.

as for speeds, try http://www.johntp.com/2006/04/19/how-to-increase-download-speeds-of-utorrent/ it should help out
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