It is temporal, as is all art. Yet there is a distinction between performance art and other forms of visual arts. Paintings, for instance, are documented as a finished product. They are not intended to be experienced as a process. Although time decomposes them, we do all we can to preserve them.
Performance art employs the three dimensions of space and the fourth dimension of time.
Unlike theatre, performance art doesn't have to occur on stage. Yet it often does. In the alternate persona project we eliminated the stage, and brought our performance into our daily environment. Our props, audio, and lighting were provided by the world. Similarly, in performance art, our perceptions of the world are no longer removed from the experienced world and placed in a museum.