在C++中,用另一个字符串替换字符串中所有出现的子字符串的最快方法是什么？

#include<iostream>
#include<string>

std::string replaceAll(std::string& str, const std::string& from, const std::string& to) {
    size_t startPos = 0;
    while ((startPos = str.find(from, startPos)) != std::string::npos) {
        str.replace(startPos, from.length(), to);
        startPos += to.length();
    }
    return str;
}

int main() {
    std::string str = "Hello, world! This is a test.";
    std::string from = "world";
    std::string to = "C++";

    std::string result = replaceAll(str, from, to);
    std::cout << "Result: "<< result<< std::endl;

    return 0;
}