No sadly changing the transition time is not possible directly in Lay Theme -
You can change the transition time manually by using CUSTOM CSS
Which Lay Theme does offer :)
You have the ability to add CUSTOM CSS in:
"Lay options" - "Custom CSS & HTML"
There you can target the menu elements and change their transition times to your liking.
If you are unfamiliar with the basics of CSS I hope this helps you as a reference point
the second link provides knowledge on how to use the "Inspector tool"
An Example i made that change the menu elements on your website -
I took a look at what element was getting the "Transition" so that i could target it -
Then in Lay options, i added this Custom CSS
Note: i added ' !important ' at the end to give this transition time superiority over any other code that may already be in place.
It should also be noted that this is a crude example of what is possible, I just made it in the hope it helps you on the right path
Apologies for getting back to you late, thank you for your patience