[ragall]

> If you could do the same checks and caching in a few hundred milliseconds it would only improve the usability for the cashier.

No it wouldn't. Those interfaces are permanent and only get restarted once a day or if the hardware has to be rebooted. Same for Emacs: there's absolutely no need to start the editor every single time.

> You haven't made a case for why some user interfaces shouldn't start instantly

I'm not making any case, we're not in court. Startup time is irrelevant and your fixation with it is really funny (up to a point).