"急板之乐曲或乐章" can be translated into English as "a musical piece or movement in prestissimo tempo" or simply "a prestissimo piece or movement".
"Prestissimo" is the musical term for an extremely fast tempo, faster than "presto".
"Musical piece" or "movement" refers to a complete composition or a section within a larger work, respectively.
This translation accurately conveys the meaning of "急板之乐曲或乐章," which denotes a musical composition or section characterized by an extremely rapid tempo.