running code faster is the only way to consume less (Anyway Java is faster than c++) - Efficiency with Algorithms, Performance with Data Structures (CppCon)

• output parameter are not faster - it’s a myth
  • return value optimisation work better (in general)
• just say NO to linked list
• don’t use a std::map it’s a linked list
  • unordered_map won’t save us either. (also a linked list all below) => use a open addressing implementation instead, it’s maximimising cache locality.