Through eCommerce-enabled hosting, each deployment will have its own optimizations for the particular software that is designed to run it, which will provide a rapid service for online merchants. However, in small business hosting plans, this is typically oriented around shared web hosting and is designed to deliver optimal performance with the reliability as well as support that small businesses need, and will typically support Joomla, Drupal, and WordPress.
You can add eCommerce functionally to shared hosting plans. However, you will notice a lot of latency in just about everything you do.