Your ASP.NET application uses connection pooling to connect to a database. You find that the following exception is logged when the application is under heavy load:
Exception: System.InvalidOperationException
Message: Timeout expired. The timeout period elapsed prior to obtaining a connection from the pool. This may have occurred because all pooled connections were in use and max pool size was reached.
You must fix the problem without causing undue overhead to build connections.

What should you do?