efficiency question

[aliasghar25]

Hi
I have one vector of size 4 (vector<int> vec(4);) that its elements were read from a sequential file.
I have a copy of vec that its name is vec2 (vector<int> vec2(vec);)
I was investigating in performance efficiency of operations operate on containers and I found a weird and interesting thing.
When calling a function for vec and vec2 100,000,000 times, it takes 2415 milliseconds for vec and just 986 milliseconds for vec2.
Why this happens??

[o1vk4iN6]

Source code would be helpful as there simply might be a mistake.