That being said, simdjson does take an interesting approach and for just pulling out specific parts of a JSON document it is very fast.
simdjson is designed to do the opposite of what you describe - nearly all the intellectual work in simdjson was focused on parsing a whole document in one hit, not on "pulling out specific parts of a JSON document".
So, I'm quite unclear on how you could derive a measurement that made us look fast on pulling out specific parts of a JSON document. That being said, I don't have a lot of experience with the current simdjson DOM traversal code and maybe there's some terrible "buried treasure" there (I mean sarcastically - i.e. we have some dumb decisions, maybe?) that you're tripping over. But the one-shot "parse" should be fast.
Anyhow, if you could try to code up something to show parsing speeds on workloads similar to what we describe at https://github.com/simdjson/simdjson it would be very interesting. We've made the effort to make all our benchmarks repeatable - if your approach is faster it would be cool and surprising.
That latter task is a valid use case, and interesting in itself, but not something we really knew how to measure and write about. The problem is with those sort of benchmarks is that they tend to resemble a "ask yourself a question then answer it" - I couldn't think of a good way of coming up with a set of "let's query a JSON file for a specific thing" benchmark that didn't seem ludicrously contrived.