A request taking 2-3 seconds locally does not feel like a problem. In production, it becomes one very quickly. Most backend issues I’ve seen around APIs were not caused by bad logic. They were caused by requests staying open for too long. Why this becomes dangerous Long-running requests hold resources. Usually: database connections memory worker threads external API sessions One slow request is manageable. Hundreds of slow requests at the same time start creating bottlenecks across the entire system. And the worst part is that it often happens gradually. Everything works fine in staging. Production traffic exposes the real problem. Common causes 1. Too much business logic inside a single request A request comes in and the API tries to: validate data generate reports process images call external APIs update multiple systems send emails All before returning a response. This is one of the biggest architectural mistakes in backend systems. 2. Waiting on third-party APIs External services are unpredictable.…