Re: Relative performance of text-properties search functions

[Eli Zaretskii <eliz@gnu.org>]

> From: Thorsten Jolitz <tjolitz@gmail.com>
> Date: Fri, 24 May 2013 19:26:39 +0200
> 
> > You were talking about outline or org-mode, so how is .emacs relevant?
> 
> Because my .emacs looks like this:
> 
> ,----------------------------------------
> | ;; * init.el --- my Emacs Init File
> | ;; ** Commentary
> | ;; * Prerequisites
> | ;; ** Start Message and Start Time
> | ;; ** Setup Parts
> | ;; ** Environment
> | ;; ** Loading Emacs Lisp Libraries
> | ;; ** Debugging
> | ;; * [Screen Input Keys Cmd Enter Exit]
> | ;; ** 1 (info "(emacs)Screen")
> | ;; ** 2 (info "(emacs)User Input")
> | ;; ** 3 (info "(emacs)Keys")
> | ;; ** 4 (info "(emacs)Commands")
> | ;; ** 5 (info "(emacs)Entering Emacs")
> | ;; ** 6 (info "(emacs)Exiting")
> | ;; * [Basic-Edit Minibuf M-x Help]
> | [...]
> `----------------------------------------
> 
> with outline-minor-mode and outshine.el activated. 

Which is exactly the problem I was alluding to.  You may think that
when you fold the buffer text like that that Emacs has no problems
displaying that -- after all, those are just a few lines, right?  But
in fact, the way Emacs display works, it must traverse the entire text
of the portion of the buffer that corresponds to those header lines,
skipping the folded text (which has the invisible text property), and
displaying the rest.  Add to this replacing display properties, which
you say will have to change all the time (whatever that means), and
you might have annoyingly slow display operations, because replacing
display properties are treated specially by the display engine, and so
it constantly looks for them when it iterates over buffer text.