A complete save is done even if a document is unchanged. This used to be different in older versions of LibreOffice, IIRC.
Yes, this is intentional, save is now always functional, and the icon is slightly different if there are unsaved changes. *** This bug has been marked as a duplicate of bug 97930 ***
(In reply to Aron Budea from comment #1) > Yes, this is intentional, save is now always functional, and the icon is > slightly different if there are unsaved changes. > > *** This bug has been marked as a duplicate of bug 97930 *** And why would that be? If there are no changes, the save operation should simply not be started—if only for the fact that in bigger documents, it can take some time.