While I really like node.js, I always feel skeptical about "re-implemented gave X% improvement". Often a re-implementation is done because the domain-knowledge has improved significantly since the project was started. There should be an improvement even if the re-implementation was done in the same language.
When I see people talk about X% improvement because of some new tech, I always think about Fred Brooks and the No Silver Bullet essay. Nothing changes under the sun.
