One Million Rows: Testing xlfilldown Performance and Constant-Memory Design

The content discusses the performance and reliability of the xlfilldown tool, which efficiently processes large Excel datasets without excessive memory usage. A stress test processing 1,000,000 rows demonstrated rapid speeds—13,800 rows/sec for Excel and 44,700 rows/sec for SQLite—while maintaining deterministic and auditable output. This enhances data integrity and workflow trust.