uTorrent, the best BitTorrent client gets a dramatic rewrite to its disk i/o in version 3.3, which means noticeable performance gains in multi-tasking. For example, you can delete files from a torrent or move torrents to a new location, but without the usual slow-down in torrent downloading. Or, download torrents to two different drives, but with the speed of downloading to a single drive. You'll notice gains at both low and high speeds, and whether you're writing to local disk, a RAID or a network drive. You'll also experience improvements to the disk subsystem and rate limiter.