Of all conceptual paradigms of architecture, performance is the one that seeks to evaluate the efficiency of its ambitions. Opposed to an architecture for the sake of architecture, it investigates the feed-back loops between architecture and the systems it is embedded in. Isolated questions of form, process, fabrication etc. cease to be a priori conditions of architecture. Performance does not ask how a form looks like, but what it enables. It does not focus on what process was used to make a design, but on what process was able to generate in the design. Thus performance shifts the focus of interest from essence to effect. The question is not what 'something is', but 'what it does'.
Andreas Ruby, The Metropolis Dictionary of Advanced Architecture