MMS Monitoring can be used to test the performance of new code changes in a staging environment, which mirrors the production environment. The authors compared the performance of two operations: a simple Map/Reduce operation and an equivalent Aggregation Framework operation, using a dataset of 10 million entries. The results showed that the Aggregation Framework operation was significantly faster (52 seconds vs 139 seconds) and had less impact on lock percentage, memory usage, and resource utilization. This demonstrates how MMS can help identify performance issues with new code changes and optimize database performance.