Verify that statistics is updated - first step in query performance optimization
If you have a performance issue with a query, the very first step you should take before analyzing it is to update the statistics on all the tables in your database.
This is because many query performance issues are due to outdated statistics, and updating them before troubleshooting query performance may save you a lot of time.
If the query is still giving you trouble after updating the statistics, then you can begin your troubleshooting.