I have multiple GE switches with add-on switches wired to them. When I turn the light on or off from the add-on switch it is just about instant. When doing it from the main GE switch there is a slight delay for the light to go on and off. WTH doesn’t make sense.
Also there is a slight difference in delay between the zigbee GE switches compared to the Zwave ones when operating from the main switch. Forgot which one is slower, not at home now.