Router Problems

I'm with telus and i've been having troubles behind my router for a while. It's super slow. First i tried switching routers cause i figured it was prolli just a defect when the truth was, it wasn't a defect. I don't know whats wrong. All the computer on my network seem to be experiencing this problem. But the moment I take my computer off the router and directly into the modem, it jacks up the speed back to normal. I don't know whats wrong. I cloned MAC address, released renewed IP and nothing seems to make it better. Please help, thx.

Questions:

How many computers on your network?

If you did a broad sweep IP ping on your network, what are the
results? Is there one or two computers that have a higher ping?

What if you were the only computer on the router, does it have the
same speed?

Is someone running a filesharing app?

So many questions, so little time....

It seems that someone or something is hogging your bandwidth
for one reason or another. Whether there is a virus or file sharing
or something is misconfigured and broadcasts something at full-bore
all the time....something.

Below is a link to a program I like called angry IP scanner. it is simple
and does the trick.
http://www.angryziber.com/ipscan/

I would scan your entire subnet. The results on a LAN should be <1
for all unless you are all seperated but in the same building
they shuold all be <10.

I never really read this forum so PM me if you need any further help.