All reasoning is about power: the intention of reasoning is to bring different people into alignment with a conceptual understanding of the world, and that kind of alignment is the primary source of social power. The difference lies in method, not in intention. Habermas broke down reasoning modes into four general types:
- Teleological rationality: attempts to reach social outcomes through functional success (basically a 'winners are right' model).
- Normative rationality: attempts to attempts to reach social outcomes by asserting cultural or metaphysical norms as truths.
- Dramaturgical rationality: attempts to reach social outcomes by appeals to sincerity and righteousness ("I am good so you should believe me" type arguments).
- Communicative rationality: attempts to reach social outcomes by reasoning towards depersonalized consensus.
Socrates would have fallen very much in the last category: for him, argumentation was all about rationalizing the concept without regard to the individuals involved. The people he labelled as sophist all tended to fall in the third category. They were (to Socrate's mind) politicians and pundits more that philosophers, interested in promoting their aptitude for rhetoric at the expense of any particular philosophical end.
Performance art in the modern sense is almost exclusively negative dramaturgy — social statements meant to distort, defame, disrupt, confuse, or otherwise attack the sincerity of other expressions of social power — so in that sense it would invariably be a form of sophistry. But not all dramaturgy is negative. Peaceful protests, civil disobedience, impassioned pleas, etc are all dramaturgy, but they rely on the sincerity of the participants rather than questioning the sincerity of others. Performance art is intrinsically and consciously insincere: not in the bad sense of the term, but in the sense that it constantly seeks to question that which is held to be sincere.