Engineered a high-throughput backend service powering an enterprise payment analytics dashboard at Jotform to track critical KPIs like revenue, conversion rates, and AOV across multi-currency and geospatial breakdowns. Implemented 8 robust RESTful endpoints with sub-second response times, eliminating memory bottlenecks through PHP generator-based chunked batch processing and optimizing complex SQL queries across unindexed EAV schemas with in-memory aggregations. Additionally, built a secure streaming CSV/Excel export pipeline with formula injection protection and UTF-8 BOM encoding for seamless international character handling.