Every so often, when Logos hangs (usually after a morph search) and I have to force-quit Logos, I find that though the Logos icon has vanished from Finder, the actual windows do not disappear. Running ps aux from the terminal shows that gdb is running - attached to an instance of Mono. Manually killing the gdb process also gets rid of the unwanted, dead, windows.
Which raises the question in my mind - are we running debug builds, or are the builds that are released as part of the Logos beta program release builds? That is, are they optimized for performance or for debugging? I ask because this might (here's hoping) provide improved performance (if the current builds are debug builds with heavy logging, etc inside).