I do not have prestaging on - it's very strange in my case. Switching using HubConnect and Alexa (on my control hub) seems fast. Switching with Pico on my main hub displays behaviors you mentioned, switching with Pico on my controller hub and HubConnect better - more reliable and a bit faster - 2 seconds instead of 7-10.
I should note that there are hub slowness issues on my main hub that I have not resolved yet. Am slowly trying to work those out. Maybe there is a "misbehaving" device on the system dunno. I do have an Aeotec Dual Nano switch (ZW+) that seems very slow and power reporting spammy as well. Going to replace that one soon I think,
I guess I am not convinced of the value of the recessed bulbs - too many switch and dimmer complications it seems. Is cool (in a useless sort of way) to change the color of the entire room by a single voice command though..