The lag isn&#x27;t UI-related or related to the specific software stack IMO. We&#x27;ve had to technology to build extremely lag-free devices for years now, the lag is more fundamental than that.<p>Your microwave and VCR are always on - their displays are also always on, so they don&#x27;t need to be woken up before being used, they are already awake.<p>A thermostat with an always-on screen is the same, they&#x27;re already displaying information and the touch screen can be immediately used without delay - but we don&#x27;t <i>want</i> the display to be always on, because in general LCDs look awful in their environments. In general people prefer their homes to not look like server rooms with blinking lights and garish panels everywhere.<p>So there is a non-technological need to keep the screen off, and this presents a fundamental problem - before anything can be done, the screen must first be woken up. No matter how fast you make this process, at the end of the day is one extra step that the user must do before the device can be used.<p>Apple Watch detects when your wrist is held in a certain position to activate - but sensing this gesture itself introduces lag. Hell, even a simplistic &quot;on&quot; button on the device itself - even if the response is perfectly immediately - necessarily requires the time for the user to trigger the action itself.<p>You can&#x27;t work around this with better software, because at the end of the day &quot;activate device&quot; is step 1, whereas with dumb technology step 1 is &quot;use device&quot;.<p>The only real solution is for your devices to be always-on in a much more fundamental way - like your VCR or microwave - and that in some cases means e-ink screens.