The new `maxTimeMS` feature in MongoDB 2.6 allows users to limit how long an operation can run in the database, preventing unexpectedly slow queries from overloading MongoDB. This feature can be set on a per-operation basis and applies to both CRUD operations and commands. The new query optimizer introspection feature provides visibility and control over the plan cache, allowing users to diagnose performance degradation issues and gain better understanding of their system's operation. With these features, users can identify slow or unoptimized queries, prevent cascading effects from failed connections, and make data-driven decisions to optimize their MongoDB performance.