Queries or updates that take longer than expected to execute can be caused by a variety of reasons. Slow-running queries can be caused by performance problems related to your network or the computer where SQL Server is running. Slow-running queries can also be caused by problems with your physical database design.
There are a number of common reasons for slow-running queries and updates:
- Slow network communication.
- Inadequate memory in the server computer, or not enough memory available for SQL Server.
- Lack of useful statistics
- Lack of useful indexes.
- Lack of useful indexed views.
- Lack of useful data striping.
- Lack of useful partitioning.
Checklist for Analyzing Slow-Running Queries