Re: The Menu is slow, how to find out why?

[Nikolay Kudryavtsev]

Not exactly the solution you were looking for, but if you're extensively 
using the menu like this, maybe you'd be interested in using a library 
called LaCarte, available here:

https://www.emacswiki.org/emacs/lacarte.el

This is arguably a more convenient way of accessing those menus, that 
uses the normal emacs minibuffer instead of the popups, thus it would 
circumvent your main issue.