This solution’s COU cost can be significantly improved by using memory protection. You protect the frame buffer from writes. The first time it is written, you take a fault, and start refreshing every 60 Hz and leave it writeable. After some number of refreshes, you protect it again, the idea being is that the UI may now be quiescent. I do this in my Palm OS port for the same reason.

I'm intrigued by this technique! Will look into it, thanks for the tip!