I've fixed all the known bugs and error cases in sajson. If you end up using it, I'd love to hear from you.

I'll capture some scattered thoughts before my JSON parsing obsession dies down.

There's not much opportunity to take advantage of a modern CPU's superscalar execution pipeline when parsing JSON. Parsing JSON generally involves reading a character and branching. Searching for a string's ending quotes could be implemented with vector instructions (see strchr in Agner Fog's optimization manual or this tutorial) but the ROI doesn't seem high to me.

Could we use multiple threads? Maybe, if we split the input text into chunks and had each thread discover the next { or [ and optimistically begin parsing future elements. Almost certainly not worth it

Either way, sajson is approximately done. I will post benchmarks soon.