To disable that shortcut, one could
load S Voice, then press the menu key and hit "Settings." Next, uncheck "Open via the home key." That's it -- with the shortcut combo disabled, the home button should respond immediately as opposed to with a very slight delay.
However, this method seems viable only once Samsung's Terms of Service (ToS) have been accepted - only after which S Voice will launch fully. Any way to disable that key combo without having to accept ToS of a S I do not want?
Note that at this stage I do not (yet) want to uninstall S Voice. If you happen to know how to uninstall it, I'd appreciate a comment, though :-)