This registry tweak has been serving me for years to prevent utorrent from filling windows memory cache with file mappings of files I'm seeding while leaving nothing to other programs. The full description is here along with the tests, I'm sorry, but it's in Russian, you could probably autotranslate to make some sense of it.   Description goes like this: If you're seeding a lot of files, they will need to be read by utorrent at some point to actually seed them. The Windows doesn't know anything