Add orjson to benchmark suite

[packysauce]

fixes #62

it's pretty quick!

[mre]

Cool! Thanks @packysauce. ✌️

[mre]

it's pretty quick!

It's indeed pretty fast. The cost, however, is more unsafe code:

• ijl/orjson@2c473a5
• ijl/orjson@ed18c84
• ijl/orjson@6bcfd63

Not saying this is necessarily bad; it's just a design decision that they made.

I believe that it should be possible to reach similar performance without unsafe code.
For that, we'd have to do some more profiling to find bottlenecks and find better ways to make use of Rust's strengths. For example, by refactoring the codebase we could make use of parallel encoding/decoding. We could then use rust-evmap to build up a hashmap datastructure in a lockless way.
That's just an example and it might not be that easy, but adding such functionality to a codebase with a lot of unsafe code can be quite difficult from my experience. 😉

Now I wonder if I should create an issue for that to give it a try... 🤔