I looked at the original code from Part 1 and it really makes me confused at why you would implement most of this in this way - even if your goal is to simply test the bottlenecks of various STL implementations. I don't think it's a terrible series and I think the author has the right idea, but the choices in implementing things like taking in a large string and returning a large string when you're basically saying the use case is CSV record parsing is strange.