The length property of an array is used more efficiently than putting a local variable

In the CLR via C # I see the following text, the length property of the array, after a special processing, in the loop, the direct use of the property ratio, the length of the local scalar in the high-efficiency.

Therefore, for the efficiency of the program, many times can not only assume that this is efficient, need to go to practical practice, perhaps the result is their own unexpected.

The length property of an array is used more efficiently than putting a local variable