I had the opposite reaction. Updating from the Apple TV 4, the AT&T TV app no longer lags. Now, it starts right away, and channels load in moments instead of seconds. With the new remote, it's much easier to navigate the UI (clicking the outer ring).I literally bought the new Apple TV to hope it fixed it. Still terrible
The Cloud DVR is still a little glitchy; when using the touch surface to pause during playback, it doesn't always activate scrubbing; you have to press the play/pause button and then go to the touch surface, and then scrubbing doesn't respond the way it does in Movies, where clockwise advances and counterclockwise rewinds. There's an arbitrary point where scrubbing will switch from ff to rewind, which is frustrating.