16MB is pretty slow for a school. You see it is designed so that many people can access one connection. If say just 10 people are using the Internet you would only have a 1.6MB connection. If it's in school hours or around this time that could be nearly a 100 people odd using the Internet. However I doubt that there is someone being a bandwidth hog, and your connection won't be that dramatically cut . You will probably find those on Messenger at the same time as you are slowing it down. I generally think your school's Internet is slow