JV has 48 acceleration during boost, best in the game. Once hysteresis kicks in, and assuming there aren't evil bad obstacles you're tripping over, speed will always fall to exactly 2363 as JV's maintenance during boost is -1. One frame of acceleration gets us to 2411, then our speed slips down again under hysteresis.
JV's normal maximum is 2368, which is significantly slower than 2411, so braking to avoid hysteresis is right out. This is basically thanks to the extremely powerful acceleration moving us well past the usual maximum in a frame. And while we could hypothetically accelerate at 2368 speed, getting to 2416, this would only be the case if we weren't under hysteresis mode, and dropping our speed to 2320 just so we can reach 2416 two frames later is almost certainly not worth it.
So let's just focus on chopping down the slow half of our hysteresis time and getting to our next cycle sooner. Dropping down to 2363 with one, two, or three frames of braking means we should only brake at 2376, 2389, or 2402 speeds.
I'll just math out the average speeds for zero to three frames of braking:
2387.00 - No braking, cycle length 49 frames
2392.68 - 1 frame braking, cycle length 37 frames
2397.56 - 2 frames braking, cycle length 25 frames
2399.00 - 3 frames braking, cycle length 13 frames
Well, the good news is that brake tapping has a more significant advantage here. Not counting drifting, it's even 0.5% faster at its best. There's room for error so that you're still at an advantage even if you brake a frame or two early.
I'm not sure how RTA-viable it is, though. I hear you players can get crazy-good, so something like this might be within the realm of possibility. If you are able to add in the effort of braking in the middle of whatever crazy snaking you're doing, there is a chance it can save a bit of time. Problem is that over-braking for a single frame means you start the next cycle at less than top speed, which can ruin whatever savings you got with brake tapping to begin with.
How consistently can you tap a button for exactly two frames? I'll give you an easy test: Training -> JV -> any track. Once the timer is running, start at 0 speed and tap A (unless you changed controls and made that B instead). 12 km/h is one frame. Jet Vermilion is done with its first gear in 8 frames, by the way, so if your speed exceeded 96 km/h, you went into the second gear's 6 km/h per frame acceleration. If you need a better feel, swap the A-B controls for a moment as a way to practice the feeling of trying the brake tapping, seeing where you accelerated to, before you go try boosting and brake tapping then (oh, don't forget to fix your controls back to normal by then).
So during boosts, TAS would just get the 3 frame brakes and that's the end of the story. Well, almost, as there may be some tweaks in picking which frame braking to fit the remaining boost time. I would advise RTA to go for 2 frame brakes, as that requires 2.4 brake taps per second rather than a more frantic 4.6, any errors in timing is less painful, and the peak of 2 frame brakes is only minimally worse than the peak of 3 frame brakes. Even so, the precision needed to save even a frame is very high, I'll leave it to RTA players to decide if it's worth practicing.
On a side note, if I'm throwing decimal around in this post, I really should just stick with decimal in my script. Sorry about the whole hexadecimal thing. Would you prefer my next script version goes with decimal values?
When the CPU spawns in determines which side of the track it will spawn on and go down. Spawning on frame 2885 makes it go down the left side, spawning on frame 2886 makes it go down right, 2887 makes it go down left again...
EDIT: I think part of how it works is that there are invisible lines that when crossed will spawn an object. These can be horizontal, vertical or diagonal. When you cross that line is part of what determines object behavior. 
