BRAKES!!! Stop Argh!

[jsbihn]

Hey all,
So I am curious about what might be the culprit....
My brakes are working.... BUT they dont seem to be slowing the rig down as it used to.
I am noticing that by the time I get to the stop sign/light that the rig is still moving faster then it normally would.
No it isnt a driver error :-P
So I am wondering if this could be a pad issue or a booster issue?
It does have about 135,000+ miles on it and I bought it as the second owner. i dont know if the brakes were replaces in the first 100,000 miles or not.
I dont have any lights, and really if i stomp the brakes the truck will stop hard, so it has me slightly confused.

Any thoughts on how to check this out?
Thanks