I submitted a benchmark here: https://github.com/krausest/js-framework-benchmark/pull/185. It will hopefully be merged soon. It performs better than Redux and MobX and slightly worse then optimized pure React there. I will send PRs to more benchmarks in the next week.
It completely avoids setState (doesn't call it in the background).
It fixes it in a sense that your state is updated synchronously. The state is just a plain object. If you update it, it gets updated. Renders are triggered asynchronously in a batch however to be performant.
Also setState can be troublesome when you deal with complex data structures - like arrays, collections or getters/setters. This is when this library really shines.