Hello Lukas, Thanks for the tip! In the meanwhile I discovered the following: - It depends on the monitor: an another monitor connected to the VGA port is working! Only with this particular monitor the EDID (monitor identification) is transfered endless. - The HDMI port (of the docking station) is working fine. - Even the "problem monitor" is working fine with the VGA port of the docking station (but not with the VGA port of the notebook). For the moment it is OK for me that I have to use the VGA port of the docking station. But I have no idea about the reason ... Best regards, Matthias Am 24.09.2014 um 23:00 schrieb Lukas Jirkovsky:

On 21 September 2014 12:35, Matthias Klein wrote:

...

Hi,

I tried to switch on my Lenovo L530 Notebook from Debian testing (KDE) to Arch Linux. Installation was no problem, but when I connect a second monitor to the VGA port the whole system gets very slow / unuseable. (The same hardware constalation works without problems under Debain testing.) I know this is not very helpful, but I noticed exactly the same thing with my Asus UL30A this weekend (and KDE, too). I know it used to work before, but I haven't used the second monitor for a long time, so it may be broken for quite some time.

I have found only a partial solution, and that is to disable effects before connecting a monitor. After the second screen is connected, even the cursor movement becomes unbelievably choppy, but after a while everything goes to normal for me. When I left the effects on, the system stayed unusable.

Lukas