Here are some factors to consider before you start analysis:
Is this a new query? If not, has it been rewritten?
Has the query just started to perform poorly, or has it performed poorly all along?
Have there been any changes to the database or table? Have columns and/or indexes been added?
Have any buffer pools been added, deleted, or resized? Have any cache bindings changed? Have any caches been resized?
Has the data changed significantly?
Have you upgraded Adaptive Server?
