If you host your sites on a dedicated hosting server, you would expect that they'll perform ultra fast and that the access speed to them shall depend only on the Internet connection of the website visitors. Having said that, this is not going to be the case in the event that the hosting machine has bad network connectivity or relies on a network card, which simply just can't deal with high volume of website traffic. If this is the case, it'll take a while for your sites to load if lots of people open them at the same time or visitors could see error messages. As a result you might lose customers as most likely many people will not return to your website in the event that they have experienced issues or slow loading speeds. This is why you must pay attention to the network components of any new hosting server that you get and not just to the main hardware like Processor, Random access memory or hard drive.