Comment 49 for bug 639659

The solution to the memory leak problem that Sander (s4nder86), John Doe (cs1-6pics), and youen (youri-56-gmail) describe happening on windows can be solved by qbittorrent managing the cache and disabling the windows cache.

Windows cache does not do a good job of releasing the memory used for caching torrent data. The faster you are uploading or downloading, the more likely you are to see this problem. This used to be a problem for utorrent as well back when Windows Vista first came out. After many bug reports and arguing with users, they solved it by changing the default of utorrent to disabling the windows cache and having utorrent manage the caching of reads and writes.

I have attached a pic to show the default cache management settings of utorrent. qbittorrent needs to manage the caching of data to solve this phantom memory leak. I call it phantom because qbittorrent itself won't show in task manager as using the memory, but once you close/shutdown qbittorrent you get all the memory back.

http://imageshack.us/photo/my-images/690/cachesettings.jpg/