"Performance Best Practices: Query Patterns and Profiling" discusses the importance of designing the right query patterns and profiling query behavior for smooth application performance. Key points include using the latest drivers, avoiding large unbounded documents, issuing updates to only modify fields that have changed, updating multiple array elements in a single operation, and isolating analytics queries from operational workloads. Profiling queries with `explain()` or the Query Profiler helps identify performance issues, while tools like MongoDB Compass and mtools provide additional insights into query patterns and performance optimization. The series continues with indexing as the next installment.