Godot vs. Rapier
Rapier is an open source physics framework written in Rust.
This project pits godots built-in physics against Rapier. It uses godot-rust to integrate rustcode in godot using gdnative.
note: Godots built-in physics has an open issue for the instability when stacking a lot of rigid bodies: https://github.com/godotengine/godot/issues/2092