First of all try clearing cookies,browser history and cache,avoid running electronic devices at once,upgrade your modem or router to a newer model and have a periodic check in your modem ventilation, or do you using P2P (Peer to Peer) file sharing programs? If so then try turning the file sharing program off, as file sharing programs use up allot of bandwidth some broadband providers limit the speed you can use the internet if you are using file sharing programs.

If you turn off the file sharing program your broadband speed goes back to normal .