A lot of those benchmarks have print statements in them. Maybe they're not profiling that part? But I'd pretty much outright reject any sort of benchmark program that prints anything. Printing to the screen is the death of performance. It also looks like they're including a lot of Boost stuff as well. Basically, their C++ implementations are questionable and look like they might also be pre-C++11.
In my mind, it's easier to write slower C++ because the language is doing a lot more for you without you necessarily being aware of it. The lack of `std::move` in use with all their potentially needless classes makes me skeptical. C++ and C should have relatively comparable performance.
