Many things can affect the Broadband speed.  The most common ones are:

1.    Broadband is advertised as up to 8Mbs (for example), this defines the maximum speed that can be achieved by your connection not the minimum, the minimum could be as low as a quarter of 1MB (256kbs). To check your broadband speed visit http://www.speedtest.net/

2.    Broadband is a WAN (Wide Area Network) therefore all the users on the network share the bandwidth from the supplier, if you have 10 people in your area connected to the service and they are all browsing, your speed would probably remain unaffected, but if three of them are downloading files, this could impact on the overall speed you receive.  This kind of service restriction is called Over Subscription and most ISP (Internet Service Providers) will not advertise how many users a system is capable of coping with at once (the contention ratio).

3.    LAN (Local Area Networks).  If your broadband is shared in the office or home the router will divide the bandwidth / speed between all connected. If, like on theWAN, a user is downloading a large file this could impact on all the other machines connected to the LAN.

4.    A faulty device or noise on the Line.  Often described as attenuation both are acceptable within certain levels of tolerance.  Outside of these ranges they can indicate a hardware fault which could be as simple as corroded copper wires increasing the resistance on the lines.  However, it could also indicate a fault on the exchange modem.  You may experience many different symptoms, varying speeds and frequent service disconnections.  In these cases have your Broadband supplier check out the lines and equipment, but firstly make sure that nothing on your LAN is causing the problem.