Performance
Performance is completion of a task with application of knowledge, skills and abilities. In work place, performance or job performance means good ranking with the hypothesized conception of requirements of a task role, whereas citizenship performance means a set of individual activity/contribution (prosocial organizational behavior) that supports the organizational culture. In the performing arts, a performance generally comprises an event in which a performer or group of performers present one or more works of art to an audience. Usually the performers participate in rehearsals beforehand. An effective performance is determined by competency of the performer - level of skill and knowledge. Spencer and McClelland in 1994 defined competency as "a combination of motives, traits, self-concepts, attitudes, cognitive behavior skills (content knowledge)" that helps a performer to differentiate themselves superior from average performers. A performance may also describe the way in which an actor performs. In a solo capacity, it may also refer to a mime artist, comedian, conjurer, or other entertainer.
Science
The objective world of science has nothing in common with the world of things-in-themselves of the metaphysician. The metaphysical world, assuming that it has any meaning at all, is irrelevant to science.
A. D'Abro, The Evolution of Scientific Thought from Newton to Einstein (1927) footnote, p. 152.
Performance
"For me, the most important thing is the element of chance that is built into a live performance. The very great drawback of recorded sound is the fact that it is always the same. No matter how wonderful a recording is, I know that I couldn't live with it -- even of my own music -- with the same nuances forever."
Aaron Copland, quoted in Classic Essays on Twentieth-Century Music. ISBN 0028645812.