plasmashell leaks memory uncontrollably

I'm not sure if this is a problem with the plasmashell executable itself, or the the nvidia libraries, or perhaps plasmashell not interacting with the nvidia libraries correctly, but for the past several months I've noticed that the memory usage of plasmashell creeps slowly and consistently upward the longer it is running.

This is at the level for me that within a day or two after (re)starting it, it is taking up all of my 12 gigs of ram and my my swap space engages and my system starts thrashing to the point that it takes minutes to get to a console to killall plasmashell. If I'm not sure if I'll even get to that point, I do SysRq+F (Sometimes it locks up completely -- presumably due to a kernel panic -- if I don't catch the extensive thrashing before too long, but that's a secondary issue.)

This problem began several months ago (I was sort of expecting someone would quickly patch it, so I lived with it for a bit) so unfortunately I can't point to a specific version number. I did run apport-valgrind on plasmashell (output to be attached), which is what implicates the nvidia drivers.

Happy to provide any additional information requested or to try other versions of these applications.

ProblemType: Bug
DistroRelease: Ubuntu 17.10
Package: plasma-workspace 4:5.10.5-0ubuntu1 [modified: usr/share/plasma/look-and-feel/org.kde.breeze.desktop/contents/lockscreen/LockScreenUi.qml]
ProcVersionSignature: Ubuntu 4.13.0-37.42-generic 4.13.13
Uname: Linux 4.13.0-37-generic x86_64
NonfreeKernelModules: nvidia_uvm nvidia_drm nvidia_modeset nvidia
ApportVersion: 2.20.7-0ubuntu3.7
Architecture: amd64
CurrentDesktop: KDE
Date: Mon Mar 19 15:48:15 2018
InstallationDate: Installed on 2012-01-06 (2264 days ago)
InstallationMedia: Kubuntu 11.10 "Oneiric Ocelot" - Release amd64 (20111011)
SourcePackage: plasma-workspace
UpgradeStatus: Upgraded to artful on 2014-12-03 (1202 days ago)