Why did Kaspa need the Rust rewrite before the Crescendo upgrade could happen?

Kaspa's Rust rewrite (KIP-1, known as Rusty Kaspa) had to be completed first because its performance improvements provide the foundation the network needs to sustain 10 blocks per second and beyond. Rusty Kaspa is the project that rebuilt Kaspa's core node software in the Rust programming language, which is designed for speed and reliability. Running at 10 BPS places far greater demands on every node — more blocks to validate, more data to store, more bandwidth to use — and the old software could not have handled that load. For a beginner, this means the upgrade was only possible because Kaspa's developers first rebuilt the engine before pressing the accelerator.