To determine whether your Microsoft® SQL Server™ system is performing optimally, you should establish a server performance baseline by taking performance measurements over time. Each set of measurements should be compared against the same measurements taken earlier.
After establishing a server performance baseline, compare the baseline statistics to current server performance. Numbers far above or far below your baseline are candidates for further investigation. They may indicate areas where the server needs to be tuned or reconfigured to improve performance.
For example, if the amount of time to execute a set of queries increases, you may want to examine the queries to determine if they can be rewritten or if column statistics or new indexes need to be added.
At a minimum, measurements should be taken to determine: