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I'm not entirely sure what the problem is. I'm using the same version of Emacs on three different computers ( laptop, work, home ), and the problem only shows up on one machine ( the home machine ).

Basically, when I'm using Emacs ( 24.4, compiled from downloaded tar.gz ) Emacs seems to take quite a while to do any sort of vertical rendering. Scrolling, finding a file ( using a custom ido vertical mode ), helm... anything that requires Emacs to render vertically seems to slow down Emacs.

It doesn't seem to have to do anything with how many lines are in the current buffer, the slow-down happens even in the scratch buffer.

I've also tried starting with emacs -Q, and it still happens.

Oddly, it's CPU/memory usage stays pretty low while this rendering is happening.

I took a video of the weirdness, just in case my description wasn't super clear.

Sean Hagen
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  • Did you have GTK3 installed? You should compile it with this option `--with-x-toolkit=gtk3`. – Tu Do Jan 08 '15 at 06:45
  • I've tried with GTK3 and without, it's the same either way. The only thing that seems to make any difference was disabling xft. I'm trying again with only `--without-xft --without-m17n-flt --without-selinux` as options. – Sean Hagen Jan 08 '15 at 06:54
  • Even with `--without-xft`, the rendering is still slow. – Sean Hagen Jan 08 '15 at 07:06
  • Just downloaded 25.0.50.1 from git, and it's facing the same issue. So... maybe this is an issue with one of the libraries that Emacs is using, and not Emacs itself? Any idea how I could track down what's taking the rendering so long? – Sean Hagen Jan 08 '15 at 07:32
  • What is your OS? Maybe could try it with another window system? Meanwhile, you can use Emacs in terminal while investigating this issue. – Tu Do Jan 08 '15 at 09:03
  • Try [unicode-fonts](https://github.com/rolandwalker/unicode-fonts). Sometimes a bad font configuration can cause Emacs to slow down. –  Jan 08 '15 at 10:05
  • Indeed the *drawing* is very slow (*rendering*, to me, means something more like computing what we want to draw). Maybe a bad interaction with the way your X server is optimized. I see something vaguely similar (but to a *much* lesser extent) on my AMD E-350 system, and IIUC it's because Emacs uses "old-style 2D drawing" whereas the graphics driver is optimized for "new style 3D drawing". – Stefan Jan 08 '15 at 14:06
  • @TuDo I'm using Ratpoison in Ubuntu 14.10. I'll give it a go in Unity, see if that helps. – Sean Hagen Jan 08 '15 at 18:07
  • @Stefan I'll see if I can play around with my graphics driver settings when I get home, see if that helps. – Sean Hagen Jan 08 '15 at 18:08
  • @lunaryorn I'll give that a shot too. – Sean Hagen Jan 08 '15 at 18:08
  • @lunaryorn no luck with unicode-fonts. – Sean Hagen Jan 09 '15 at 07:08
  • Sorry to hear that. It helped me, but it was just a blind guess. –  Jan 09 '15 at 07:09

2 Answers2

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So I finally restarted my computer, and tried running Emacs with the Unity WM. It ran fine, so I logged out and tried it again in ratpoison. Ran fine.

No idea what the problem was, or what the solution was. Just commenting to prevent people from wondering what happened.

Sean Hagen
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I had this problem with emacs 24.3 on xubuntu running xfce 4.10, even for completely trivial text files It only appeared in the "xemacs" (gtk) version, it ran fine in a command shell with the DISPLAY env var unset. I used the xfce Settings / Window Manager Tweaks dialog to switch display compositing ON and that fixed it!

Ian
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