Optimizing SQL queries and reducing CPU usage in SQL Server can be achieved through several strategies:

  1. Indexing: Proper indexing can significantly reduce the amount of data that needs to be read from the disk, which can reduce CPU usage. Make sure your queries are using indexes effectively, and consider adding new indexes if necessary.
  2. Query Optimization: Rewrite your queries to make them more efficient. This can include avoiding subqueries, reducing the use of joins, and eliminating unnecessary calculations.
  3. Use SET NOCOUNT ON: This statement stops the message indicating the number of rows affected by a T-SQL query statement from being returned, reducing network traffic.
  4. Avoid Cursors: Cursors can be very CPU-intensive. If possible, try to rewrite your queries to avoid using cursors.
  5. Batching: If you’re inserting, updating, or deleting many rows at once, try to batch the operations into smaller chunks to reduce the load on the CPU.
  6. Optimize Database Design: Normalizing your database can reduce data redundancy and improve performance. However, in some cases, denormalization can improve performance by reducing the number of joins needed.
  7. Use Stored Procedures: Stored procedures are compiled once and stored in executable form, so the database engine can reuse the execution plan and avoid the overhead of compiling and optimizing the query every time it is run.
  8. Update Statistics: SQL Server uses statistics to create query plans. If your statistics are out of date, SQL Server might not choose the most efficient plan.
  9. Limit the use of Temp Tables: Temp tables can be a performance hit. Try to limit their use or use table variables or CTEs (Common Table Expressions) instead.
  10. Hardware Upgrade: If your server’s hardware is not sufficient for the workload, upgrading the hardware (like adding more CPU cores, or using faster CPUs) can help reduce CPU usage.

Remember, it’s important to thoroughly test any changes in a development environment before applying them to your production database.