First off all: save points.
1 - energy temple 1
2 - open waters 1
3 - kelp forest 3 (after mother nature)
4 - sun temple (after getting the crystal)
5 - abyss 1
6 - final boss
This means the run would be done in 7 segments. Those are the save points I was going to use in my run. I agree that wall-jumping can be a bit tricky, but it all comes down to memorization. Also the hardest segment of the run would be the body (the sun temple brair boost isn't so scary once you get a hang of it) - you'd have to time where it's better to take damage then heal, rather than avoid enemies. The reason behind the low number of segments is the fact that each save costs a lot of time (sometimes more than 10s) which is, most of the time (assuming you have everything memorized), more than it would allow you to save.
Energy boosting items will be your best friend during boss fights. The default attack value is 1. A spicy roll gives a +1 energy bonus, which in other words means attack x2. IIRC energy boosters save a whooping 30s on mother nature, about 15s on sun worm, and 10-15s on creator2. My plan was to get a spicy roll in energy temple 2 and kelp forest 3 (one per boss is enough), then a volcano roll in the body 2. Dealing more damage doesn't affect creator3. Getting an extra +energy item for creator5 (face) is pointless since even if it would be in your way, getting it would cost more time than it would save.
Speaking of food - I have to mention the divine soup (+2 speed, 5 heal). Following the right
recipes you can get your hands on it as soon as you get to mid energy temple, then you spam it with the food glitch for the rest of the game. You can get all but one ingredient before even getting to the temple. The last missing piece is jelly oil (dropped by blue jellyfish). You can either kill those by using energy form or by binding a boulder and releasing it above them. The first option ends up being faster because until that point you'll be using royal soups (+2 speed) for faster movement. The first blue jelly you encounter after getting EF is at the bottom left of energy temple 2. Jelly oil has a drop chance of, I think, 25% or so - that explains why I wanted to save at the energy temple. The +2 speed boost saves tons of time. When testing, I was over a minute faster at open waters 1 (just after energy temple) compared to not getting the soup.
Another important thing is the food glitch - it does something more than just let you cook without wasting ingredients. After performing the glitch, there's a small time window where the game will ignore triggers. This allows you to do two things: skip certain cutscenes, and get oob (out of bounds) in a few places. I don't really remember which cutscenes can be skipped, or partially cut, so you'll have to test every possible one (there's no solid rule to which can and which cannot be avoided). As for going oob, it saves time on two occasions: you can get through kelp forest 1 to the veil 1 and use the glitch there to get to the right side of the area (which renders both of the older veil early methods slower), and you can get from veil 2 to veil 3 way sooner by using this. For some reason you can only get oob (or return to the map) either from the bottom or the right side of the map. On top of that, the area around the map change trigger can't end with a wall, or you won't be able to go out of the map. So because of those reasons, this glitch doesn't save time anywhere else. I had an idea of getting to the body early, without nature form, but the area under the tentacle is a tunnel and it's too narrow to pass even in fish form. Then again I heard rumors that some people could clip through the "singing door" in the sun temple in FF and I never managed to do that. My run ended in the testing phase, so I never really tried to pull off any of those clipping glitches - might be worth a shot, though. If all fails you can still easily enter the body in any given form.
One last tip: you can kill creator1 in less than a second with a well placed brair.
Feel free to comment or ask questions.
Also, good luck with the run.
