If your on a 100Mb/s port, then yes 33TB is the theoretical amount of traffic you can run thru it, but that is using 100% all the time, which you would see slow down's across the board for all your surfers because no one fills the line up to 100% all the time. My traffic peaks around 4pm CST, but around 4am it's less than 20% of my peak.
So if your doing 20TB on a 100Mb/s pipe your getting pretty close to your limit before there is slow downs during the peak traffic use
Does the host show an mrtg where you can see max and ave use ?? What are they ??