Worked on the eclipse-scout/scout.rt repository to enhance the ListBox component’s performance when handling large datasets. Focused on Java-based performance optimization, the work introduced a new LargeSetListBox class and refactored AbstractListBox to improve the efficiency of value synchronization between the UI and underlying data tables. This architectural enhancement enabled scalable management of checked rows and contributed to faster UI responsiveness during large-dataset operations. The changes were implemented with clear commit traceability, supporting maintainability and future improvements. Emphasized unit testing and maintainable code structure, ensuring that the optimizations could be reliably extended and integrated into ongoing development efforts.