It might be lots of overdraw in the general web case, but for a text editor almost everything the app renders is going to be shown on the screen. The exception

It might be lots of overdraw in the general web case, but for a text editor almost everything the app renders is going to be shown on the screen. The exception is a bit of stuff just outside the scroll viewport, so it can respond instantly to scroll requests. This feels like a good tradeoff to me.