Resizing X frame is slow in Xubuntu when compositing is enabled

[Toshio Ito]

My environment:

- Xubuntu 14.04 (fresh installed)
- emacs24: 24.3+1-2ubuntu1
- xorg: 1:7.7+1ubuntu8
- Xorg driver: intel

Problem:

When "display compositing" is enabled, resizing X frame of Emacs is
slow, i.e., the frame cannot follow the cursor smoothly.

How to reproduce:

- Make sure "display compisting" is enabled.

    $ xfce4-settings-manager
    Select "Window Manager Tweaks"
    Select "Compositor" tab
    Check "Enable display compositing"

- Start Emacs in window mode

    $ emacs -q

- Resize the Emacs frame by dragging the frame edge.

Workaround:

Disable display compisiting.

[Thaddaeus Tintenfisch (thad-fisch-deactivatedaccount)]

It seems that the emacs window is rather slow when redrawing its content. I did some testing in a virtual environment on a low end host system and every application window was showing the delayed resizing behavior. Enabling the built-in compositor increased the delay somewhat.