I was thinking about the lag of the system when I tried it on the preproduction car earlier this weeks and I do have to say the nav section did work pretty well. I didn't notice any u usual activity when putting in addresses, etc that I can remember. The lag seemed to occur when I was trying to go I to the active steer and ride preference options. Hoping that's all resolved on the production vehicles but I did like the nav. And that screen is beautiful!! This guy entering info reminded me of that.
I also like the way they put some options at the top of the touch screen like turn list and a few others I forget right now. Very useful as I access the turn list quit often when in nav mode.