Well, that seems to be an unfounded assumption that I'm considering only powerful machines, especially since possible challenges on small devices were mentioned

Well, that seems to be an unfounded assumption that I'm considering only powerful machines, especially since possible challenges on small devices were mentioned in the OP. In fact, I done a fair amount of ARM coding so I understand what you are trying to say. Nevertheless, your comment seems to point out smartphones may be less powerful, but sheds no light on what the delta might be for boot performance or how you can be confident it's say, more than a few hundred milliseconds. Maybe it is, I haven't isolated and investigated that single difference enough to form a reasonable guess. Have you?