[squidsk]

I think you have a misunderstanding of how things work. Indexes improve the performance of the database by speeding up searches of tables when the conditions of searches use columns that have been indexed. For example a query of the post table for all posts by a particular user (i.e. userid column) is much faster if the userid column is indexed than if it isn't. The cost of indexing a column (or groups of columns) is that it takes up space. The one thing that is not a cost is performance.