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

Your test code is checking a pathological scenario of excessive string concatenation. (The string-search part of the test could have probably been omitted, I bet you it contributes almost nothing to the final results.) Excessive string concatenation is a pitfall that most languages warn very strongly against, and provide very well known alternatives for, (i.e. StringBuilder,) so what you are essentially testing here is how badly these languages fail under scenarios of perfectly expected failure. That's pointless.

An example of a similarly pointless test would be to compare the performance of various languages when throwing and catching an exception in a tight loop. All languages warn that exception throwing and catching is abysmally slow. They do not specify how slow, they just warn you not to expect anything. Therefore, to go ahead and test precisely that, would be pointless.

So, it would make a lot more sense to repeat your test substituting the mindless string concatenation part (s += "X") with whatever construct is offered by each one of these languages precisely for avoiding string concatenation. (Such as class StringBuilder.)