From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eli Zaretskii Subject: Re: Enriched/Org is a colorful Org Date: Thu, 11 Apr 2013 20:27:47 +0300 Message-ID: <83wqs99dv0.fsf@gnu.org> References: <87a9p79gnv.fsf@gmail.com> <20130410095450.GA31506@kuru.dyndns-at-home.com> <83a9p69x0c.fsf@gnu.org> <262C4E11-6D4B-4033-A619-1702CC8D0F94@gmail.com> Reply-To: Eli Zaretskii Return-path: Received: from eggs.gnu.org ([208.118.235.92]:35813) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UQLHZ-0004tT-1S for emacs-orgmode@gnu.org; Thu, 11 Apr 2013 13:27:34 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UQLHX-0005Ts-NN for emacs-orgmode@gnu.org; Thu, 11 Apr 2013 13:27:32 -0400 Received: from mtaout20.012.net.il ([80.179.55.166]:46419) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UQLHX-0005TY-Ek for emacs-orgmode@gnu.org; Thu, 11 Apr 2013 13:27:31 -0400 Received: from conversion-daemon.a-mtaout20.012.net.il by a-mtaout20.012.net.il (HyperSendmail v2007.08) id <0ML300600POXU500@a-mtaout20.012.net.il> for emacs-orgmode@gnu.org; Thu, 11 Apr 2013 20:27:29 +0300 (IDT) In-reply-to: <262C4E11-6D4B-4033-A619-1702CC8D0F94@gmail.com> List-Id: "General discussions about Org-mode." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-orgmode-bounces+geo-emacs-orgmode=m.gmane.org@gnu.org Sender: emacs-orgmode-bounces+geo-emacs-orgmode=m.gmane.org@gnu.org To: Carsten Dominik Cc: emacs-orgmode@gnu.org [Please CC me on responses, as I'm not subscribed to this list.] > From: Carsten Dominik > Date: Wed, 10 Apr 2013 21:58:06 +0200 > Cc: emacs-orgmode@gnu.org > > > I beg the Org developers to please be very careful when introducing > > expensive display features such as overlays into Org. Org already > > puts the Emacs display engine to its limits in many of its popular > > features; > > this is interesting input, I was not aware of this. Has this been discussed before, can you point me to relevant threads, and what are the symptoms of the display engine being at its limits? You won't find explicit discussions of this, except maybe a random comment from me here and there. There aren't too many discussions about the display engine in general; maybe it's my fault. But you can find indirect evidence to what I say in quite a few reports about slow redisplay. Here's one example (it's just the first one that popped up on Google): http://lists.gnu.org/archive/html/emacs-devel/2011-09/msg00276.html Note how two display features: bidi and hl-line -- each one of them cause significant slow-down in Org buffers, and almost nowhere else. This is just an example. I keep bumping into similar issues frequently enough to lead me to the conclusion you see above. In general, hiding from display large parts of a buffer, and using a lot of display strings and overlays that add to buffer text or replace buffer text with something else -- these all make redisplay much more expensive. In particular, moving overlays disables many redisplay optimizations, so e.g. any mode that moves overlays as result of post-command-hook will considerably slow down display and degrade user experience. After hacking the display code for a few years, it is painfully clear to me that its basic design assumed that such use cases are rare. Org mode makes these assumptions more and more false, and it does that faster than the CPU speed improves ;-) For these reasons, and as long as we don't have any development going on that aims at a complete redesign of the display engine, I think every feature, especially one expected to be popular, that adversely impacts redisplay efficiency, should be considered very carefully, and the various alternatives for its implementation assessed also from this aspect. HTH