Make sure indexes are being used, and rebuild themIndex useanalyzing
If an index is useful for a query, is probably using it. However,
you need to make sure. Analyze the way is executing your application's
queries. See for information on
how to do this.
In addition, over time, index pages fragment. Rebuilding indexes improves
performance significantly in these situations. To rebuild an index, drop it
and then re-create it.