Is C++ fast?

A library that I work on often these days, meshoptimizer, has changed over time to use fewer and fewer C++ library features, up until the current state where the code closely resembles C even though it uses some C++ features. There have been many reasons behind the changes - dropping C++11 requirement allowed me to make sure anybody can compile the library on any platform, removing std::vector substantially improved performance of unoptimized builds, removing algorithm includes sped up compilation. However, I've never quite taken the leap all the way to C with this codebase. Today we'll explore the gamut of possible C++ implementations for one specific algorithm, mesh simplifier, henceforth known as simplifier.cpp, and see if going all the way to C is worthwhile.