Why is constexpr performing worse than normal expression?

I know there is a similar question about this: constexpr performing worse at runtime.
But my case is a lot simpler than that one, and the answers were not enough for me. I'm just learning about constexpr in C++11 and a wrote a code to compare its efficiency, and for some reason, using constexpr makes my code run more than 4 times slower!
By the way, i'm using exactly the same example as in this site: https://www.embarcados.com.br/introducao-ao-cpp11/ (its in Portuguese but you can see the example code about constexpr). Already tried other expressions and the results are similar.

constexpr double divideC(double num){
    return (2.0 * num + 10.0) / 0.8;
}

#define SIZE 1000
int main(int argc, char const *argv[])
{
    // Get number of iterations from user
    unsigned long long count;
    cin >> count;
    
    double values[SIZE];

    // Testing normal expression
    clock_t time1 = clock();
    for (int i = 0; i < count; i++)
    {
        values[i%SIZE] = (2.0 * 3.0 + 10.0) / 0.8;
    }
    time1 = clock() - time1;
    cout << "Time1: " << float(time1)/float(CLOCKS_PER_SEC) << " seconds" << endl;
    
    // Testing constexpr
    clock_t time2 = clock();
    for (int i = 0; i < count; i++)
    {
        values[i%SIZE] = divideC( 3.0 );
    }
    time2 = clock() - time2;
    cout << "Time2: " << float(time2)/float(CLOCKS_PER_SEC) << " seconds" << endl;

    return 0;
}

Input given: 9999999999

Ouput:

> Time1: 5.768 seconds
> Time2: 27.259 seconds

Can someone tell me the reason of this? As constexpr calculations should run in compile time, it's supposed to run this code faster and not slower.

I'm using Visual Studio compiler.