Go to Applications (or wherever you have installed FrostWire)
Right click on the the FrostWire Icon > Get Info (or just Press Cmd+I after you’ve selected)
Make sure FrostWire won’t nap when it’s in the background.
Otherwise, you may start a long running transfer and OSX Mavericks will put FrostWire to sleep and your transfer won’t finish.
This is only a temporary work around to this new issue introduced by Mavericks and its awesome power saving tactics, we’re working on an update so that you don’t have to do this in the future.