I'm using uTorrent Server build 27079 with Ubuntu 10.10 Server. When I'm trying to download large file (>20 Gb) to NTFS volume, ntfs-3g driver starts throttling (top shows mount.ntfs-3g taking 100% CPU), torrent downloading speed drastically decreases to 10-100 Kbps, and respective partition becomes unresponsive for read/write operations. Turned file pre-allocation off and diskio.sparse_files on, no help so far.
This is definitely big file downloading by utserver problem, because smaller torrents are loading as expected - with up to 3 Mbps speed, and stopping utserver service removes cpu load/fs lags.
People on uTorrent forums says this is related to ntfs-3g. No solutions how to fix though.