Use Flat Catalog on Categories and Products
Enable Flat Catalog
Using Flat Catalog Category and Flat Catalog Product is a great solution for optimizing Magento store. This will help to reduce queries to database a lot.
Access to your Magento Admin Panel then System > Configuration > Catalog > Catalog > Frontend
When flat catalog is enabled in Magento then all the above product attributes (id, name, price) are kept in one table named like catalog_product_flat. Then Magento fetches product data from the flat table rather than joining all the other smaller tables.
You have to rebuild Flat Catalog using Cache Management and Index Management.