What makes for a great performance?
When the actor disappears into the role and you only see the character? Yes.
When the viewer is pulled in and made to feel what the character is feeling? Yes.
When every movement large or small is directed at embodying a character? Yes.
When dialogue, good or bad, is delivered in a way that it feels right, feels true to the character? Yes.
When the performer combines all the arts of their craft - voice, language, costume, make up, movement, every ounce of their being? Yes.
When it is, above all, engrossing or entertaining? Yes.
Therefore, the indisputably greatest performance ever captured on film is the dogs who play the shrews in this film.