[pjc50]

> the constraint efficiency of game developers: 16 ms window to do all your processing

This is the only one that really matters. It also implies a complete redesign of how "responsiveness" is handled, because the usual failure mode of slow GUIs is to get blocked on a whole cascade of updates which have to be done in series. Immediate mode GUIs are a lot better for this because the programmer knows that they can't call out to get some data; you render what you're given, either it's arrived on this frame or it hasn't.