The performance cost is crazy when format string is parsed at runtime. Implementing all that subtle functionality correctly takes up a lot of CPU time. Accord

The performance cost is crazy when format string is parsed at runtime. Implementing all that subtle functionality correctly takes up a lot of CPU time. According to my quick test, on Visual Studio 2012, even simplest sprintf with just one parameter seemed to take about 1 microsecond to execute. Of course clang and gcc seem to sometimes compile whole format parser away. At least... printf ("Hello World!\n"); ... is optimized into a simple "puts("Hello World!");". Of course iostream << operator runtime performance is also pretty horrible. Each << invocation seem to call streambuf::sputn (or sputc) separately. On VS2012, simplest stringstream test... ss << "value: " << intVal << endl; ... outputting one variable into it and turning the result into a std::string took about 3 microseconds. (Although it was a very quick test, a number of things might be suboptimal in the test code.)