You can use the Query Processor categories on the Server Status Tool to view the status of SQL queries. With this information, you can then determine if any of the SQL queries are causing performance issues. Inefficient SQL Queries can affect performance, for example, a poorly constructed SQL Query could cause a high load on the server.
For more information refer to:
If you suspect that an SQL query is the cause of slow performance, you should refer to the Inefficient SQL Queries section of Diagnose Client Performance Problems.
If you experience performance issues while working with SQL Queries, in particular those that relate to the Event Journal, you should also check the size of the historic and event files for your database. For more information, see Historic Data Problems.