In general BitTorrent clients are not the most “resource using” applications. But how do they actually affect, and slow down Windows?
Thepcspy compared the three most popular BitTorrent clients. And it seems that uTorrent is indeed entitled to be called “the lightweight client”.
The mean boot time of Azureus, Bitcomet and uTorrent were compared on a Windows XP Pro clean install.
However, to put things into perspective, Norton Internet Security 2006 caused a 57.78% slowdown.