Why do std::string operations perform poorly?

Question

I made a test to compare string operations in several languages for choosing a language for the server-side application. The results seemed normal until I finally tried C++,

Answer 1

So I went and played a bit with this on ideone.org.

Here a slightly modified version of your original C++ program, but with the appending in the loop eliminated, so it only measures the call to std::string::find(). Note that I had to cut the number of iterations to ~40%, otherwise ideone.org would kill the process.

#include 
#include 

int main()
{
    const std::string::size_type limit = 42 * 1024;
    unsigned int found = 0;

    //std::string s;
    std::string s(limit, 'X');
    for (std::string::size_type i = 0; i < limit; ++i) {
        //s += 'X';
        if (s.find("ABCDEFGHIJKLMNOPQRSTUVWXYZ", 0) != std::string::npos)
            ++found;
    }

    if(found > 0)
        std::cout << "Found " << found << " times!\n";
    std::cout << "x's length = " << s.size() << '\n';

    return 0;
}

My results at ideone.org are time: 3.37s. (Of course, this is highly questionably, but indulge me for a moment and wait for the other result.)

Now we take this code and swap the commented lines, to test appending, rather than finding. Note that, this time, I had increased the number of iterations tenfold in trying to see any time result at all.

#include 
#include 

int main()
{
    const std::string::size_type limit = 1020 * 1024;
    unsigned int found = 0;

    std::string s;
    //std::string s(limit, 'X');
    for (std::string::size_type i = 0; i < limit; ++i) {
        s += 'X';
        //if (s.find("ABCDEFGHIJKLMNOPQRSTUVWXYZ", 0) != std::string::npos)
        //    ++found;
    }

    if(found > 0)
        std::cout << "Found " << found << " times!\n";
    std::cout << "x's length = " << s.size() << '\n';

    return 0;
}

My results at ideone.org, despite the tenfold increase in iterations, are time: 0s.

My conclusion: This benchmark is, in C++, highly dominated by the searching operation, the appending of the character in the loop has no influence on the result at all. Was that really your intention?