Why is there a delay in changing channels on vizio hdtv with uverse?

older sylvania non hd tv worked fine, no hesitation in changing channels. now with new hdtv, there's a one or three second pause or sometimes the channel never changes. owner's manual doesn't refer to it.|||Your TV is just a monitor, The lag time in changing channels is due to your U verse box. Your not changing the channel on the TV your changing the channel on the U verse box.