In the TOS of some hosts, they say something about the system usage not allowed to go over so and so percent (like 5 or 10% at this one place I looked at), exactly what would you be doing to use that percent of the system? Lets say a couple of visitors were downloading a file from the site, would that cause it to go to 5%?
It really won't be people downloading at the same time, that would cause heavy net in/net out usage. This is talking about CPU usage, and the strain the processor is receiving. This, as mentioned before, is caused by scripts requring the server to 'think' abnormally high amounts, lessening the amount of percentage to be shared among other clients.