Worked on the st0x0ef/stellaris repository to deliver a targeted performance optimization for the OxygenRoom component. The main feature involved refactoring the storage of oxygenated block positions, replacing an ArrayList with a HashSet to improve lookup efficiency during oxygenation checks, especially on large maps. This adjustment reduced CPU overhead while maintaining existing functionality and behavior. The work demonstrated a practical application of data structures and performance optimization techniques using Java, focusing on measurable improvements rather than broad changes. No major bugs were addressed during this period, and the update laid groundwork for further enhancements in data handling efficiency.