there is little delay to activate PopUp menu with MMB in RhWIP cca 2 second. But….is not everytime, just sometimes and i haven’t exact steps to replicate it, unfourtanelly (i know “stupid” information but…). Below system info.
There is a setting in the Rhino options to control the delay (in milliseconds) of the MMB pop-up window. Perhaps it can be adjusted to a shorter period of time in your Rhino? Mine is set to 15 ms and it works flawlessly. Despite that it says “Right mouse button”, that particular setting actually controls the delay of the MMB, too.
I’ve a friend with a very big and customized pop-up that’s experiencing the same delay.
It may depends on how much icons and images has to Upload?
It maybe that the copy/paste of the image retain the original fullsize dimensions instead of shrinking it? (my2cents)