This scenario comprises the following FastFormat code, and functional equivalents for all other libraries examined:

    std::string            arg0   = "abc";
    const char             arg1[] = "def";
    stlsoft::simple_string arg2   = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    int                    arg3   = -10;

    std::string  sink;

    fastformat::fmt(sink, "The first param '{0}', and the second '{1}', and the first again '{0}'. Then the third '{2}'. Finally, the last '{3}'"
                  , arg0, arg1, arg2, arg3);

This is the test/performance/performance.test.three_strings_one_integer performance test included in the FastFormat 0.2.1 beta 6 distribution.