You running your internet through a modem? unplug the coaxial cable and put your finger on the end of it for about 3 seconds. Sometimes with a modem, for both satilite and DSL, static will build up and doing that every once in awhile will help.
I would also call your ISP and let them know that things have been slower then usual for you. It is possible that you might have some things on your computer that are making it run slow all together. Has there been any "slower then usual" behavior with your PC or is it just the internet?
Also try deleteing all your cookies, if not run a spyware or adware program to get rid of tracking and ad cookies (which will also cause your internet to become slow at times)
There can be several factors, but give them a shot. If all else fails, call your ISP.