I made a TAS for Space is Key which compares the current world record to what a deathless run would look like. It shows that the game is only 17 seconds away from being optimal.

I JUST GOT A DEATHLESS RUN!!!!! and I can say 2:20 isn't possible, the fastest time is a 2:21. I think the timer starts too late and maybe the splicing wasn't done perfectly. retiming this TAS by RTA timing confirms 2:21 to be the fastest possible time:

2:21.433 possible

@Nat_Cat, where do you save 7 frames?