
From what I gather [having been in a few speed runs myself, yet not knowing anything about them] it's when you go for the main chests. Usually, you skip the chest by the Coral fluffs and "speed" your way through a path to the seahorse bridge tail. You defeat the Animated there, then continue on to the next spot. The spot differs with the crew, but it is usually the "safe spot" you get to on the one path above the Anchor Bugs, but before you reach the Queen. You then go up, like you were on your way to the queen, but head to the right and make your way to the three chests. Clear enemies, open chests, then run to Queen and defeat her. Enter next area.
In the next area, you do both chests, killing whatever Animated followed you or your crew on the screen. After you open the second chest in the Undersea Ledge, you rush past the remaining Grunny Subs and onto the next area.
Open the chest, continue on.
Run past all the Grunny Subs to the area where the safe is. After the Grunny Sub Commander is killed, people usually die.
End. xD