[solarkraft]

(I couldn't verify this quickly, but it's something I've heard a few times)

E-Ink Carta uses an LCD layer for the color filter, so it has standard E-Ink response times. These things seem to have multiple pigments, which have different weights and are separated from each other by quickly pulsing the display back and forth right, which takes a long time.

For this kind of separation waveforms probably matter a lot more, but hobby applications seem to have been doing fine with custom waveforms. They may not perfectly respond to the current temperature or have optimal ghosting prevention, but they do (from all examples I've seen) produce good images. Getting fast updates seems to be mostly a function of daring to drive the device with high power (which can lead to stuck pigments if overdone, but this can often be corrected with some flashing).