How can a small difference in input string cause a large difference in std::regex_search performance

Question

How can the small change in the command string can cause such a large performance difference. Is my regex wrong? The intent is to extract the (possibly multiline string) between the two markers '|>'. I compiled this code using Visual Studio and Microsoft C++ compiler.

    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;
    }