Legacy modernization / performance

Context

eShopWorld operated international ecommerce and financial systems where reliability, correctness, and release risk mattered. The relevant work involved legacy C# services, relational databases, and financial processing behavior that had to remain understandable before it could be changed safely.

Paulo’s role

Paulo worked as a backend engineer on legacy services and financial-system improvements. His role was to understand existing behavior, isolate the real performance constraint, and make the system faster without treating a rewrite as the default answer.

Constraints and risks

• The process was business-critical and connected to financial outcomes.
• Existing behavior had to be preserved while performance changed significantly.
• The legacy codebase required careful investigation before modifying implementation details.
• Database and application responsibilities needed to be separated by evidence, not preference.

Decisions and trade-offs

The improvement favored a targeted modernization path: understand the current behavior, identify expensive filtering and query work, and move the right work closer to the database where it could execute efficiently. That choice avoided a broader rewrite and reduced the surface area of release risk.

The trade-off was that this approach required more upfront analysis than a direct code rewrite. The benefit was a smaller, testable change connected to the actual bottleneck.

Outcome and evidence

The approved source material states that the work reduced a critical financial process from roughly 30 minutes to milliseconds and contributed to recovering approximately EUR 300,000.

The same source material also states that Paulo was selected to help onboard an external senior engineering team and act as a technical bridge in a high-risk modernization context.

Evidence limits

This page intentionally generalizes internal implementation details, financial process specifics, and organization-sensitive context. It is based on the approved resume and experience notes supplied on 2026-08-28.