I have a laptop and an external screen (different resolution). When connecting the screen I choose to disable the laptop and output everything on the external screen. In KDE4 the switch was quite fast but in plasma it takes significantly longer, i.e. there is a longer pause before applications and then the deskbar become visible and it takes even longer till the desktop is usable again.

Worst, sometimes the laptop screen does not gets activated after the monitor is detached. Even after a reboot the screen stays blank.

In KDE4 it was also possible to put both screens on top of one another. However, now it is almost impossible. I think this might be related because I already had problems in KDE4 but after connecting/reconnecting the monitor I was always able to get the right results. Maybe the slow switching makes it impossible now.

Reproducible: Always