During November, Donald Dole developed a configurable Data Encryption Key cache lifetime feature for the mongodb/libmongocrypt repository. He refactored the cache initialization logic to use a default expiration constant, improving code maintainability and consistency. Donald also introduced an option to set custom cache expiration in milliseconds, allowing runtime tuning for diverse workloads. This work, implemented in C and leveraging skills in caching, configuration, and cryptography, reduced DEK fetch latency and improved encryption throughput while preserving security guarantees. The feature enables clients to optimize performance for client-side encryption scenarios, reflecting a focused and well-scoped engineering effort within a short timeframe.