What's the difference between that and cynder? I know they both come from Meta/IG but I wonder if cynder is an evolution from skybison or is it more of a different approach?
Cinder and Skybison are different approaches. Skybison was a ground-up rebuild of the object model and interpreter, whereas Cinder is a JIT that lives on top of CPython.
Kind of! In my fork I run microbenchmarks on each PR. So you can see on, for example, https://github.com/tekknolagi/skybison/pull/456, that the change had a 3.6% improvement on the compilation benchmark. If you expand further, you can see a comparison with CPython 3.8. Unfortunately Skybison is still on 3.8.
