With most providers, cheap standard broadband is provided via an ADSL connection. This is where phone lines are used to transport your broadband.  These wires are made out of copper and are used to connect your home with Openreach on-street cabinets to give you your internet.  The reason why most cheap broadband isn't that fast is that copper isn't a great material to send information through. The longer the copper wire is, the more it will slow down your speeds.  That's why homes that are nearer to their on-street connection boxes are able to get faster internet than houses that are further away.