Plasmashell severely leaks memory when the wallpaper is configured as slideshow. Whenever the wallpaper changes, the memory usage goes up. The rate of the leak can be very steep with high resolution and/or dual monitor setup.

I'm not sure whether the memory leak is caused by plasmashell itself or a plugin, but I can literally watch the memory usage of plasmashell grow as the wallpaper change (either by the configured interval or manually).

Steps to reproduce:
1. Configure wallpaper as slideshow, for testing purposes, a short time out could be used, e.g. 1 sec.
2. Observe the memory usage of plasmashell: grep '^Vm' /proc/$(pidof plasmashell)/status