Just so there's no misunderstanding between the two words. The Dictionary meaning of Both words:
1. Acting: Art of representing a character on a stage or before a camera by means of movement, gesture, and intonation. It is the work of an actor or actress, which is a person in theatre, television, film, or any other storytelling medium who tells the story by portraying a character and, usually, speaking or singing the written text or play.
2. Performance: It is the art of doing something successfully; using knowledge as distinguished from merely possessing it;
So yeah, her performance as an emotionless drone, was spot on. Whether she conveyed the character, that's a whole different story. That's not to say she can't act or that her action sequences can be something that will work in GitS. And also, you completely ignored my reference to Under My Skin. Where her character matches that of Motoko in that sense that she's questioning who she really is.