Chrome Version: 69.0.3494.0 (Official Build) dev (64-bit)
Chrome OS Version: 10888.0.0 (Official Build) dev-channel caroline
Chrome OS Platform: Caroline (Samsung Chromebook Pro)

Please specify Cr-* of the system to which this bug/feature applies (add
the label below).

Steps To Reproduce:
(1) Use a three finger swipe to trigger the overview

Actual Result:
The overview is only triggered if you move your fingers at a certain rate or above.

Expected Result:
More precisely, the speed of the overview animation should be dependent on the speed of your three fingers. This is how Mac OS does it.
One way to implement this would be to prepare for the entry into overview the moment three fingers contact the touchpad, and then as the finger moves upwards, the animation progresses, until a set finger position is reached, at which point the animation has finished. 
The progress of the animation between the start and the end could be some function of the progress of the fingers between the start and preset end point. 
The function could incorporate some form of bounce or non-linearity near the start and the end, in accordance with whatever the material design spec recommends.
This is feasible as there are no other gestures that occur after three fingers have been laid onto the touchpad. The three finger click can be triggered on removing the three fingers from the touchpad, or after a certain timeout, or either, barring this when the overview animation progresses past a set threshold.

What is the impact to the user, and is there a workaround? If so, what is
it?
If a design as described above, or similar to it, were to be implemented, it would increase the appearance of responsiveness for this section of chrome os. Currently the animation seems choppy and discourages the use of the overview.
Note: The choppiness is a long standing issue, and I have observed it with my chromebook powerwashed, on stable, beta and dev channel, all the way back from chrome 64 through chrome 69