Comparing performance of shared_ptr

I decided to compare the performance of shared_ptr in C++ when passed by const reference, by value, and by reference. Also, I compared the pros and cons of using these ways of passing an argument to a function:

const ref: 2056 ns // fastest
value:     3948 ns // slowest
ref:       3252 ns

• const ref: Can modify the value of the class instance but cannot change the shared_ptr itself
• value: Can modify the value of the class instance and change the shared_ptr (but the latter is limited to the scope of the function)
• ref: Can modify the value of the class instance and change the shared_ptr (the changes are propagated globally)

In the above analysis, passing shared_ptr by const reference is the fastest.