"Hacker's Delight" by Henry J. (Hank) Warren. Despite the unfortunate title[0], it teaches (with code) numerous tricks, algorithms, ideas, that really improve performance and function of programs.
[0] not "hackers" as in those who try to crack into systems, but rather as in those who enjoy writing professional, clever, and efficient code.
[0] not "hackers" as in those who try to crack into systems, but rather as in those who enjoy writing professional, clever, and efficient code.