UTorrent 2.2.1 Build 25302 is the last stable version without ads of the 2.x branch. Unlike many torrent clients, it does not hog valuable system resources allowing you to use the computer as if it weren't there at all. uTorrent was designed to use as little CPU, memory and space as possible while offering all the functionality expected from advanced clients. Most of the features present in other BitTorrent clients are present in uTorrent, including bandwidth prioritization, scheduling, RSS auto-downloading and Mainline DHT (compatible with BitComet).
UTorrent is an efficient and feature rich BitTorrent client for Windows sporting a very small footprint.