The 10-Second Test

Before committing the company to this path, I needed empirical proof.

I isolated the system's worst offender: a heavily nested list endpoint that took a grueling 10 seconds to resolve in the legacy Java environment. I built a quick data migration script, ported the necessary schema to PostgreSQL, and rewrote the endpoint logic in FastAPI.

The result? The FastAPI endpoint executed in under 1 second, returning the exact same JSON payload as the legacy system.

The theory was validated. We had our technical leverage point.