Across the fire, Riga was binding a struggling deer with his usual brutal, callous efficiency.
Why does the author use the word efficiency here? I use Cambridge Dictionary and it says "efficiency" means
the good use of time and energy in a way that does not waste any
Does it literally mean that Riga was binding the deer without wasting energy and time? What is "brutal, callous efficiency"? I feel that I missed something. Please analyse that context for me.