interesting indeed
I have had no interest in getting further into the firmware itself, but now that you talk about this, maybe (although I am not well versed) it might be worth the time spent to look in to this.
The fact that the kobo clara HD (with kodo start thingy and koreader) is in my experience faster, specially when compared side by side, despite the inkpad 3 having "better" specs really bugs me, so likely there is (hopefully making it easier to look into) some processes causing overhead.
Oh well. baby steps I guess.