Just as school math taught switching between polar and Cartesian coordinates, performance and domain problems become tractable when you rephrase them. Examples from the talk: Zeller's computational calendar moving February to the end; doubling + decimal division (n/5 = 2n/10) as the human analogue of bit-shift approximations; Euclidean a-functions for tricking bounded arithmetic into useful answers; Chrono's explicit abstraction switches between durations, calendars and structures.