You should follow the following practices in designing and developing your site to avoid database performance problems:
Use Repository caching features to optimize database access. See SQL Repository Caching in the ATG Repository Guide.
Use queues to batch database transactions, rather than performing each transaction individually. See Batching Database Transactions.
Avoid using database queries that might result in table scans of large tables. See Avoiding Table Scans.
Run your database server on a separate machine from your application servers, or at least allocate a separate CPU.
