Not really a problem, but something im trying to understand.

Basically i used to connect my pc to the internet via a wire to my router(because my pc was not wireless), and this was connected to a phone extension wire to the main socket, now with this i used to get 1mb, which is what ive had for years and was told i could not get any higher because of my shitty exchange not upgrading, so thats fair enough not alot i can do about that.
Now recently ive had a problem with the extension so ive plugged the router directly into the master socket test socket and im now getting about double the speed(2mb instead of 1mb, cant complain )

So im wondering why is this? surely a extension wire and a couple of house phones connected would not cripple my internet speed by half? or could it