Jerry Lewis, VP of an IBM practice, discusses website performance and scalability for eCommerce. He shares horror stories of performance issues causing major revenue losses and customer complaints. Website performance is important because slow sites hurt sales and customer experience. Common causes of bad performance include inefficient code, database issues, and third party integration problems. To achieve good performance, websites must be designed with performance in mind from the start, with strategies like caching, efficient database usage, and infrastructure tuning.