I would be thrilled to disable PiP in the guide if it would make it more responsive. Note, I don't have a problem with all delays; a delay when changing channels is perfectly acceptable - how many people actually flip through channels nowadays rather than looking at the guide and going directly to a desired program? If I am wanting to check what is on next tuesday, again I have no problem with some seek/delay while the information is retrieved.
However, if all I want to do is check what is on channels 300-400 at this very second, out of necessity I need to access 10 or 20 'pages' very quickly. To my mind, I am accessing a simple, text-based, information system, which is actually downloaded ahead of time and stored.
The problem seems to be the PiP, in particular HD PiP.
As it stands right now, I hate navigating. On occasion, it has frustrated me to the point of turning off the tv and doing something else.