And my hunch is that they did not close all the corners with this fix... TO prove that - just configure: pref->advanced->diskio.use_partfile to false, close utorrent, delete *utorrentPartfile*.dat files, start a *new* torrent, and see if the problem is gone... I should have guessed that a while ago... But sorry, I'm lost, is it normal when adding "big" torrents (ex 5x 20 GB = 100 GB), it takes about 30-40 min to start downloading because of Disk overloaded, then with standard Disk overloaded (often several times a minute, if it's a 100% overloaded, can last more than 10 seconds, causing a cut of the download speed) ??? With pref->advanced->diskio.use_partfile to false : And what happens with uTorrent ? Is it normal this situation : 1) When add a new torrent, immediately create files with final size. (few seconds) 2) Add some data (what are they ? zero-filled ?) in the files (about ~3 GB / min processed so it requires about 30 min for 100 GB), normal step ? 3) Start download when all torrents have completed steps 1 and 2. Normal "Disk overloaded" issues. Thanks.