Just today I received an Email from Shelly support in which they state:
Zitat
The delay from the hardware button comes from the fact that there is 800ms when the unit desides whether it was long pushed, double pushed and etc.
This is no news but in previous email, they never stated this with the same clarity.
I have suggested to them that they "give the user the option to turn off long-press and double-press. Secondly, you could allow users to configure the long-press duration and the double-press speed." (800 ms seems very long to me)
Also, I am still not 100% convinced that the delay is due to double- and long-press functionality, for two reasons:
1. if the delay is caused by the device not knowing whether a button-press is the first press of a double-press or just a single press, then there should be no delay after a double-press (because there is no more ambiguity). But the delay exists also after a double press.
2. the problem does not occur in the Shelly dimmer (version 1). I believe it also has the double and long-press feature but there is no delay.