Besides the built-in Thinkpad R400 monitor (1440x900) i use external EIZO S1931 (1280x1024). I have kscreen set to disable the built-in monitor when connected to a dock with the external monitor and to re-enable it when disconected. 

Everything worked really seamlessly in KDE 4, even on this old machine it was fast, so you connect the laptop to the dock and the desktop, panel and windows were resized and switched to the new monitor in 2 second and vice versa when the dock was disconnected.

With Plasma 5.2.2 this whole interchange process took soooo long - like 30 secs or more. A with 5.3.0 it is same but even the kwin crashes during the transition, leaving windows without decorations and without ability to switch between them, and restarting the X server and KDE is the only option then.

I am not sure what kind of information you need to trace this problem. Let me know, I would like to help and provide what is necessary.


Reproducible: Always

Steps to Reproduce:
1. Enable external monitor and disable the built-in by connecting the laptop to the dock


Actual Results:  
It took over 30 secs for the panel and desktop to resize. 
The kwin than crashes.

Expected Results:  
The resize and screen-switch should be much much faster. The kwin should keep working.

# lspci | grep VGA
00:02.0 VGA compatible controller: Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller (rev 07)

# glxinfo | grep OpenGL
OpenGL vendor string: Intel Open Source Technology Center
OpenGL renderer string: Mesa DRI Mobile Intel® GM45 Express Chipset x86/MMX/SSE2
OpenGL version string: 2.1 Mesa 10.5.4
OpenGL shading language version string: 1.20
OpenGL extensions:
OpenGL ES profile version string: OpenGL ES 2.0 Mesa 10.5.4
OpenGL ES profile shading language version string: OpenGL ES GLSL ES 1.0.16
OpenGL ES profile extensions:

Drivers: extra/xf86-video-intel 2.99.917-5