I use a Lenovo Thinkpad T420 laptop, which has Intel integrated graphics (gen 2) and 
runs Fedora 24. If I use the laptop's displayport connector to connect to one external monitor,
then switch to another monitor with a different resolution (eg. from 1920x1200 to 2560x1440) or the opposite) plasmashell (sometimes?) starts a completely runaway memory consumption - 
my laptop has 8G of ram and within a few seconds after plugging into the second monitor, the machine is almost not accessible due to thrashing. 

I have been able to see plasmashell consuming > 5GB of resident memory before I managed to kill it.
It appears to continue to accelerate until the oom killer kicks in.. 
I increased swap space to buy myself some time. 

It happened most recently today, with plasma-workspace-5.8.5-1.fc24.x86_64.
The 1920x1200 was connected via a DVI to displayport adapter, while the 2560x1440 screen was connected with 
a plain displayport cable, if that matters.