I've implemented several major database and performance improvements:

1. Connection Pooling with HikariCP
   
   • Added HikariCP for efficient connection management
   • Configured separate pools for SQLite and MySQL with optimized settings
   • Implemented fallback to direct connections if pool initialization fails
2. Statement Caching System
   
   • Added statement caching to reuse prepared statements
   • Implemented proper cache clearing and resource management
   • Added automatic cleanup of statement resources
3. Query Result Caching
   
   • Implemented intelligent caching for read queries
   • Added time-based expiration and cache invalidation
   • Created smart cache eviction based on related table updates
4. Transaction Management
   
   • Added proper transaction handling with commit/rollback support
   • Implemented functional interfaces for transaction operations
   • Created async transaction execution with proper error handling
5. Enhanced Batch Processing
   
   • Improved batch operation efficiency with transaction support
   • Optimized batch grouping for similar operations
   • Added automatic cache invalidation during batch operations
6. Database Optimization
   
   • Added database optimization commands (VACUUM, ANALYZE)
   • Created indexes on frequently queried columns
   • Implemented periodic cache cleanup tasks
7. Performance Monitoring
   
   • Enhanced query tracking and pending operations monitoring
   • Improved error handling and reporting for async operations
   • Added cache hit/miss tracking with efficient memory usage