I think where Hathora shines today is in its ease of use, both in getting started and in managing complexity as you add features.

That being said, there are a number of features that make Hathora performant and easy to scale for realtime multiplayer games -- you can read about some of them on the architecture page: https://docs.hathora.dev/#/architecture

I plan on adding benchmarks in the coming weeks to better quantify perf and scalability