This should not be marked as a "solution". I have the same problem with my Roku3. Changing batteries in the remote,or restarting the router or Roku does not fix it. This is the problem: after watching a program for, say 10 minutes, if I return to the selection menu using the back (arrow) button, there is a lag of 7 seconds from the time I press the button to when the navigation executes. After that, I am able to navigate normally with no lag, unless I stop to pause on a selection for a while, and then the 7 second lag reappears when I attempt to navigate further. In other words, the lag only happens on the initial contact with a navigation button after a period of non-use. After that, the navigation command is processed without any lag. Because of this, it seems that the lag is not due to a problem with the remote, batteries, or the Roku unit, but with the upload of the command to the Netflix servers, or with the server's response time.