[Falell]

The ParsedJson type is immutable and accessed mutating iterators (up and down the tree, forward and backward through members and indices).

My immediate thought is to compare it to rapidjson, which I've used before. The paradigm of mutating iterators seems awkward at first but should be just as powerful as rapidjson's Value. For example, both approaches end up doing a linear scan to find an object member by name.

The fact that rapidjson supports mutation of Values and simdjson does not has huge implications (as mentioned in the simdjson README scope section), I suspect this tradeoff explains most of the performance differences as I know rapidjson also uses simd internally.

[hnaccy]

Is there a reason these fast json libraries seem to favor doing linear scan for object representation?

[yoklov]

Faster to build than a hash map, less code (which is also better for icache), etc.

JSON Objects tend to have few enough values that it doesn't matter a ton anyway.