To jumpslash, or to not jumpslash, that is the question.

Dannyb:"how high does a jumpslash have to start from for the gravity increase to outweigh the time it takes to actually do the jumpslash?"

This question is more complex than it seems, as a jumpslash affects both your y-vel and link's gravity. Firstly its sets link's gravity to (0,-1.2,0) instead of the usual (0,-1,0). Additionally, if you start the jumpslash in the air link's y-vel is set to 4.5, while if you start if from the ground it is set to 5. Link's y-vel follows the following rule:

vy_{i+1} = max( vy_i + gravity_y, -20)

**note gravity is only changed to (0,-1.2,0) after the speed / position update for that frame**

From standing on the ground, it takes 9 frames pressing A to reaching the same height as when you pressed A.
If it were at a high enough ledge, it would take 22 frames from pressing A to reach terminal velocity -20

From the air, it takes 7 frames from pressing sword(ish item) to reach the height you pressed it
Same as for the ground, it takes 22 frames from pressing sword(ish item) to reaching the terminal velocity of -20.

As an example of how this can be useful:
From a sidehop, it takes 25 frame from pressing A to reaching terminal velocity of -20, so you can save up 4 frames by jump slashing the first possible frame, depending on height differennce of final ground is relative to where you started the sidehop.