There are various methods to monitor query performance in SQL Server. One of the best ways is to analyze the query execution plan and identify the queries that can cause performance bottlenecks. Sometimes, query execution plans get changed during the query execution due to certain factors of SQL Server. Then there is a need to understand this behavior, so you can review the query execution plans to identify the change and understand the overall performance.
This can be done only if your system is persisting the required information for later analysis. The Query Store feature in SQL Server 2016, SQL Server 2017 and Azure SQL Database version provides the capability to store query execution plan information and gives you the opportunity to analyze it.