Mongodatabases performance issues were a significant problem for the author, who experienced frequent shutdowns and slow database calls due to memory issues. To address this, he tried using Mongotop and mongostat tools, but found them lacking in providing a clear view of the issue. He then turned to MMS (MongoDB Management Service) for monitoring and debugging, which provided interactive graphs and charts, custom date ranges, text and email alerts, and the ability to order slower queries by response time. With MMS, he was able to identify and address the root cause of his performance issues, including a particularly problematic query that was causing non-mapped memory usage. The author credits upgrading the database server and doing major refactoring with resolving the issue, but notes that MMS has become an essential tool for monitoring and debugging MongoDB performance.