Check Internet programs running on your computer
If your ISP is providing you the right speed, next step is to check if there any Internet programs running on your computer. Programs like torrents can consume a lot of your Internet bandwidth. If any such programs are running on your computer, stop it. Also check whether any programs are downloading their latest version or not. Close all the Internet applications and check your Internet speed again.
You can install TCP optimizer to improve your Internet speed a little bit more.