为什么在 Python 中“a operator= b”比“a = a operator b”要快一点？

Question

I have read this statement in a book called "Programming in Python 3", by Mark Summerfield. This statement doesn't make a lot of sense to me. So can you help me to resolve this little but important statement?

The augmented version looks up a's value only once,so it is potentially faster.

Chapter 1 "Python's Beautiful Heart", #6 Arithmetic Operators, p31, 4th last line

Answer 1

这很好地解释了为什么分配i=i+1比i+=1稍慢 基本上，它们在低级别对应于处理器的不同工作方式。