While the V30MZ is an 80186-compatible CPU, its instruction timings differ wildly from common expectations and are more reflective of its 1990s-era design:

• MUL is very fast on this CPU, taking 3-4 cycles. As a result, “shift plus add” ladders will almost always be slower or, at best, equal in performance.
• Using XCHG over PUSH/POP (and XCHG AX, reg over MOV AX, reg) is a popular pattern on the 8088/8086 due to the speed benefit. However, on the V30MZ, that is not the case:
  • XCHG on V30MZ always takes 3 cycles.
  • PUSH and POP take 1 cycle each for general registers. This means that PUSH/POP will be one cycle faster.
  • While MOV AX, reg is one byte larger than XCHG AX, reg, it also only takes 1 cycle.
• XLAT takes 5 cycles. Many simple CPU operations (such as SHR reg, 4 or MUL reg - both taking 3 cycles) can actually be faster!

TODO: Expand this list.