Re: Extended menu items, when are :enable and :filter computed?

[Richard Stallman]

    > Is this optimization really worth while on modern computers?

    Yes, I believe so. If the building involves accessing the file system 
    (which is rather likely for a program like Emacs) then it could take 
    some time.

I am not sure what "building" refers to here.  We are talking
about testing whether menu items are active.

You seem to say that you speculate this is likely to mean looking at
the file system.  However, to me that seems like a rather unlikely way
to control activity of Emacs menu items.

Are there really Emacs Lisp programs that control menu item activity
based on looking for files?