You initially developed a database system to manage patient records for a pilot project encompassing a few hundred patients across three clinics. The design utilized a single table to store all patient details and their respective visits, using self-joins for reporting purposes. At that time, server resource utilization was at 50%. However, the project's scope has since expanded significantly, requiring the database to accommodate a hundredfold increase in patient records. Currently, the reporting functions are failing due to excessive runtime or insufficient computational resources. What modifications should you make to the database design to efficiently handle the expanded dataset?