Any kind of "build texture atlas on startup" stuff is pretty unlikely. Just always going to be stuff that's higher-priority, likely even in terms of optimization.
(Edit: what I mean to say, more explicitly, is that I'm not liking how the "bang for buck" ratio of this particular optimization looks. As far as optimizing stuff, really, it's something I do all along the way; most releases contain a number of performance boosts in various areas. Which are often cancelled out by new features, but hey, that's how it goes!)