Since you have a 720p ,I would suggest also turning native to "off " and only selecting 720p as your resolution. I do this with my 720p plasma and it seems to allow my HR23 to work a little faster . It also seems to make the sd channels look a bit better.
Try it for a day or so,if you don't like it just change it back
Try it for a day or so,if you don't like it just change it back