From the repository's README:

> Speed. There are certainly faster JSON libraries out there. However, if your goal is to speed up your development by adding JSON support with a single header, then this library is the way to go.

It is essentially admitting to being slow(er). We are not supposed to pay for code modernity with performance. In fact, it should be the other way around.

Does someone know the innards of this library as opposed to, say, jsoncpp or other popular libraries, and describe the differences?