Developed and delivered the UI Thread Lock Contention Warning System for the facebook/infer repository, focusing on enhancing performance observability in Java applications. This feature detects and warns when synchronous locks occur on the UI thread, addressing potential performance degradation and UI stalls. The implementation involved concurrency instrumentation and performance optimization techniques, with comprehensive documentation and automated tests to ensure reliability and clarity for users. By surfacing contention hotspots, the work enables faster diagnosis and remediation of UI responsiveness issues. The approach demonstrated a strong emphasis on test automation, clear documentation, and cross-functional collaboration within the context of Java concurrency challenges.