… is from page 189 of Hayek’s important 1968 essay “Competition as a Discovery Procedure,” reprinted as chapter 12 in Hayek’s 1978 collection, New Studies in Philosophy, Politics, Economics and the History of Ideas:
Strange though this may seem at first sight, a high rate of growth is more often than not evidence that opportunities have been neglected in the past. Thus, a high rate of growth can sometimes testify to bad policies of the past rather than good policies of the present.