Bug 284291

Summary: kwin decorations draw slowly in KDE 4.7 without compositing
Product: [Plasma] kwin Reporter: S. Christian Collins <s_chriscollins>
Component: decorationsAssignee: KWin default assignee <kwin-bugs-null>
Status: RESOLVED FIXED    
Severity: normal CC: silver.salonen
Priority: NOR    
Version: unspecified   
Target Milestone: ---   
Platform: Ubuntu   
OS: Linux   
Latest Commit: Version Fixed In: 4.8.0
Sentry Crash Report:

Description S. Christian Collins 2011-10-17 18:21:00 UTC 
Version:           unspecified (using KDE 4.7.2) 
OS:                Linux

Since upgrading from Kubuntu 11.04 (KDE 4.6.2, Xorg 1.10.1, xserver-xorg v7.6 kernel 2.6.38-11) to Kubuntu 11.10 (KDE 4.7.1, Xorg 1.10.4, xserver-xorg v7.6, kernel 3.0.0-12), I have noticed a severe drop in kwin performance when drawing changes to the window decorations.  The slowness can be observed when new windows are created (the decorations are slow to be created) and when windows become active or inactive (the decorations are slow to change between active/inactive state).

Since I have been able to reproduce this problem on systems with both Intel and NVIDIA graphics cards, I don't believe this bug to be graphics driver-related.  The issue does not seem tied to any particular Kwin theme either.

Please see the following YouTube video for a demonstration:
http://www.youtube.com/watch?v=MUSRzUyjXY0

Reproducible: Always

Steps to Reproduce:
This test can be reproduced easily using the Kubuntu 11.04 and 11.10 live CDs.  For best results, use a slower PC to do these tests:
1) Open Dolphin.
2) Click the desktop to make Dolphin an inactive window.  Click on Dolphin to make it the active window.  You will observe a delay under Kubuntu 11.10 when performing this step.  To see this effect easier, you may want to disable animations and enable "outline active window title" in the Oxygen decoration settings.
3) From Dolphin's "Help" menu, select "About Dolphin".  When the about window appears, you will see the window decoration sluggish to appear around the newly-created window contents.

Actual Results:  
Window decorations are drawn slowly.

Expected Results:  
Window decorations should be drawn quickly.
Comment 1 Martin Flöser 2011-10-17 18:29:57 UTC 
are you using graphicssystem raster? If yes could you please try to use the 
native system for kwin? Just kwin --replace --graphicssystem=native in Alt+F2 
should do
Comment 2 S. Christian Collins 2011-10-17 18:36:53 UTC 
I should add that the sluggish drawing only happens with desktop effects
disabled.  With desktop effects enabled, the window decorations appear and
change immediately.
Comment 3 Martin Flöser 2011-10-17 18:41:29 UTC 
Yes I understood that and asked the question specific to that :-)
Comment 4 S. Christian Collins 2011-10-17 18:43:01 UTC 
Wow, using "kwin --replace --graphicssystem=native", the window decorations are
back to being crisp and responsive.  Now to find a way to make this setting
permanent on my system.
Comment 5 Martin Flöser 2011-10-17 19:44:19 UTC 
In 4.8 using raster should no longer be an issue for using with no compositing, because of that setting to fixed.

Setting native as default can be done in various ways:
* Kubuntu provides a settings module, but this affects all applications
* using a wrapper script for kwin and set it as the window manager in systemsettings
* using Desktop Effects ;-)
Comment 6 S. Christian Collins 2011-10-18 15:25:42 UTC 
I was able to create a wrapper script to set kwin to native rendering.  For any others who may happen by here, here is how I did it:

1) I created the following script as /usr/local/bin/kwin-native:
    #!/bin/bash
    kwin --graphicssystem=native

2) Then, I added the following to /etc/profile:
    export KDEWM="kwin-native"

That seems to do the trick.

@Martin: I would happily use desktop effects, but they bog things down on this older laptop.  XFCE would technically be a better fit for this hardware, but I love KDE so much, I don't mind if things are a bit more sluggish--it's an acceptable trade-off for all the features I get with KDE... and it's not unacceptably slow.  Thanks for all you do to make KDE awesome!
Comment 7 Silver Salonen 2011-12-26 13:49:24 UTC 
*** Bug 289849 has been marked as a duplicate of this bug. ***
Comment 8 Silver Salonen 2013-01-23 09:23:04 UTC 
*** Bug 289849 has been marked as a duplicate of this bug. ***