PTS will never be an accurate portrayal of what it will be on Live. The number of people on the PTS at any given time is a fraction of live, and the server strain won't be felt until you have high traffic times on live.
With that being said, PTS still has input lag. Can't say a word about Cyrodil, cause virtually nobody (aside from the reds that cap the map for some reason) actually go out in Cyrodil on the PTS.