Startup's Go-to-Rust Rewrite Killed Feature Velocity for a Quarter

A startup rewrote a Go service in Rust, achieving 12.1x faster API response times and 80% lower memory usage. However, sprint velocity dropped 65%, pull request processing time increased 320%, and developer productivity scores halved. The engineering manager admitted the business case would have failed if the 6-12 month ramp-up had been disclosed upfront.