It would be useful to have some comments about the relative performance difference between the two.

1. For instance, is C# simply a wrapper around the C++ version?
2. Does C++ benefit somehow by using memory-mapped files, using blt'able types to write structures directly to disk, which may not be feasible in C#. Or if such techniques are used, are C# Spans being used? Alternatively, if the underlying architecture is relatively neutral with no real significant difference between C++ and C# that would also be valuable to know.