May I know what is your speed? I am surprise if you can get full download speed if you are having 3Mbps. If you have 512kbps, then it is easily fill up. Also it depends on timing, during peak period, it will be very difficult to get full download speed as it will likely to be congested. Also it depends whether its local or overseas. There are too many factors..
Anyway, but if you are satisfied with what you are getting, then its all right.