If you host your sites on a dedicated server, you would expect that they shall perform very fast and that the access speed to them will depend only on the Internet connection of the site visitors. Nevertheless, this is not going to be the case if the hosting machine has bad network connectivity or uses a network card, which simply can't deal with high volume of site traffic. If this is the situation, it shall take a very long time for your websites to load if a lot of people open them concurrently or visitors might even see error messages. Because of that you might lose website visitors as in all probability many people will never return to your internet site in case they have experienced problems or slow loading speeds. That's why you need to pay attention to the network components of any new hosting machine that you purchase and not just to the main hardware such as CPU, RAM or hard disk drive.