输入字符串的微小差异如何导致 std：：regex_search 性能的巨大差异

问：

字符串的微小变化怎么可能引起这么大的变化 性能差异。我的正则表达式错了吗？ 目的是提取两个标记“|>”之间的（可能是多行字符串）。 我使用 Visual Studio 和 Microsoft C++ 编译器编译了此代码。command

    bool testCommandMatching() {
        const std::string group(R"(
                gcc 
                src\hello.c 
               -o bin\hello 
            )");
        const std::regex cmdRe(R"(^\|>((?:.*\s*)*)\|>)");
        bool bothMatched = true;
        {
            std::cmatch match;
            const std::string command(R"(|>
                gcc 
                src\hello.c 
               -o bin\hello 
            |>)");
            auto start = std::chrono::system_clock::now();
            bool matched = std::regex_search(command.c_str(), match, cmdRe, std::regex_constants::match_continuous);
            auto end = std::chrono::system_clock::now();
            // elapsed is less than 10 ms
            auto elapsed = std::chrono::duration_cast<std::chrono::milliseconds>(end - start);
            bothMatched = bothMatched && group == (matched ? match[1] : std::string(""));
        }
        {
            std::cmatch match;
            const std::string command(R"(|>
                gcc 
                src\hello.c 
               -o bin\hello 
            |> bin\hello)");
            auto start = std::chrono::system_clock::now();
            bool matched = std::regex_search(command.c_str(), match, cmdRe, std::regex_constants::match_continuous);
            auto end = std::chrono::system_clock::now();
            // elapsed is more than 1000 ms. How is this possible?
            auto elapsed = std::chrono::duration_cast<std::chrono::milliseconds>(end - start);
            bothMatched = bothMatched && group == (matched ? match[1] : std::string(""));
        }
        return bothMatched;
    }