New find by Tompa: grab a wall during specific lag from the game to cut the amount of lag that occurs. Mostly during bosses.

(Note: I didn't 100% check to make sure that the health-low beeping wasn't present during my tests; but on average, health was fine.)

Times that it can work:

-- Getting a heart container from a boss.

-- About a half second after getting a heart container, henceforth dubbed the "crystal transition" --- meaning, the period between receiving the container and the crystal's appearance.

-- For pendants, the rules are a little different.

(It seems to be OK to walk around in any non-diagonal direction during the major boss explosion. But there might be exceptions. Well, my first run-through of the bosses is done for now. Maybe in the future.)

Armos heart container -- 0 frames (even walking diagonally into heart is OK)
Armos pendant drop -- 1 frame (by grabbing the wall)
Armos pendant receive -- 1 frame (by not moving)

Lanmolas heart container -- 0 frames (but don't walk diagonally into it)
Lanmolas pendant drop -- 1 frame (by grabbing the wall)
Lanmolas pendant receive -- 1 frame (by not moving)

for Armos and Lanmolas pendant drop, you must have been on the bottom half of the screen when receiving the heart container.

Moldorm heart container -- 1 frame (rarely; weird, does it randomly even? don't bother.)
Moldorm pendant transition -- save 2 frames by not walking diagonally; non-diagonal is ok.
Moldorm pendant drop -- save 1 frame by not moving when receiving the pendant.

Agahnim's lightning attack - 1 frame (applicable)
Agahnim's defeat - 1 frame (applicable)

Helmasaur King's container -- 0 frames
Helmasaur King's crystal transition -- don't walk; no need to grab a wall
Helmasaur King's crystal drop -- get under it ASAP without moving around

Blind heart container -- 2 frames (frequently applicable)
Blind crystal transition -- 0 frames (but don't walk diagonally during the crystal drop)

Mothula heart container -- 0 frames
Mothula crystal transition -- 1 frame

Kholdstare heart container -- 2 frames
Kholdstare crystal transition -- 1 frame
Kholdstare crystal receive -- 1 frame by pressing no buttons (not done in this video)

Arrghus heart container -- 0 frames
Arrghus crystal transition -- 0 frames (but don't walk at all)

Vitreous heart container - 0 frames
Vitreous crystal transition - 1 frame (always applicable)

Trinexx peripheral heads explosion -- 0 frames, can even walk diagonally with a charged sword.
Trinexx during the transition to his final form -- don't walk diagonally.
Trinexx toward the end of the transition to his final form -- 2 frames LOST by pushing any button, but this might only be useful for TAS -- since charging up the sword is mandatory, otherwise.
Trinexx heart container -- hmmmmmmmm.
Trinexx crystal transition -- hm.

Ganon's heart container -- 0