plasmashell taking 94% CPU

Everything appears to be working fine, but I notice that plasmashell is taking a total of 94% CPU over 4 cores/hyperthreads.

The main thread has this backtrace when I connect with gdb:
#0 0x00007f475dcfdea7 in ioctl () at ../sysdeps/unix/syscall-template.S:84
#1 0x00007f4754aa0138 in drmIoctl () from /usr/lib/x86_64-linux-gnu/libdrm.so.2
#2 0x00007f46ad23d373 in ?? () from /usr/lib/x86_64-linux-gnu/dri/i965_dri.so
#3 0x00007f46ad26dc5c in ?? () from /usr/lib/x86_64-linux-gnu/dri/i965_dri.so
#4 0x00007f46ad26dd34 in ?? () from /usr/lib/x86_64-linux-gnu/dri/i965_dri.so
#5 0x00007f4759f9edab in ?? () from /usr/lib/x86_64-linux-gnu/mesa/libGL.so.1
#6 0x00007f4759fa059f in ?? () from /usr/lib/x86_64-linux-gnu/mesa/libGL.so.1
#7 0x00007f46ad241fee in ?? () from /usr/lib/x86_64-linux-gnu/dri/i965_dri.so
#8 0x00007f46ad242311 in ?? () from /usr/lib/x86_64-linux-gnu/dri/i965_dri.so
#9 0x00007f46ad23de65 in ?? () from /usr/lib/x86_64-linux-gnu/dri/i965_dri.so
#10 0x00007f4762138378 in QSGBatchRenderer::Renderer::renderBatches() () from /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5
#11 0x00007f476213dcac in QSGBatchRenderer::Renderer::render() () from /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5
#12 0x00007f476212e66d in QSGRenderer::renderScene(QSGBindable const&) () from /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5
#13 0x00007f476212eb2b in QSGRenderer::renderScene(unsigned int) () from /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5
#14 0x00007f4762168f50 in QSGDefaultRenderContext::renderNextFrame(QSGRenderer*, unsigned int) ()
   from /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5
#15 0x00007f47621c59b8 in QQuickWindowPrivate::renderSceneGraph(QSize const&) ()
   from /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5
#16 0x00007f476215b399 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5
#17 0x00007f47621cfd66 in QQuickWindow::event(QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5
#18 0x00007f475f5e846c in QApplicationPrivate::notify_helper(QObject*, QEvent*) ()
   from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#19 0x00007f475f5efd34 in QApplication::notify(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#20 0x00007f475e5e3de8 in QCoreApplication::notifyInternal2(QObject*, QEvent*) ()
   from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#21 0x00007f475ee38b01 in QWindowPrivate::deliverUpdateRequest() () from /usr/lib/x86_64-linux-gnu/libQt5Gui.so.5
#22 0x00007f475ee39019 in QWindow::event(QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Gui.so.5
#23 0x00007f47621cfd05 in QQuickWindow::event(QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5
#24 0x00007f475f5e846c in QApplicationPrivate::notify_helper(QObject*, QEvent*) ()
   from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#25 0x00007f475f5efd34 in QApplication::notify(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#26 0x00007f475e5e3de8 in QCoreApplication::notifyInternal2(QObject*, QEvent*) ()
   from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#27 0x00007f475e63b91e in QTimerInfoList::activateTimers() () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#28 0x00007f475e63c119 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#29 0x00007f475892efb7 in g_main_context_dispatch () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#30 0x00007f475892f1f0 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#31 0x00007f475892f27c in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#32 0x00007f475e63c47f in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) ()
   from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#33 0x00007f475e5e1e3a in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) ()
   from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#34 0x00007f475e5eada4 in QCoreApplication::exec() () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#35 0x0000563851f4fcc2 in ?? ()
#36 0x00007f475dc151c1 in __libc_start_main (main=0x563851f4f160, argc=1, argv=0x7ffd0547a3f8, init=<optimized out>,
    fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7ffd0547a3e8) at ../csu/libc-start.c:308
#37 0x0000563851f5003a in _start ()

ProblemType: Bug
DistroRelease: Ubuntu 17.10
Package: plasma-workspace 4:5.10.5-0ubuntu1
ProcVersionSignature: Ubuntu 4.13.0-17.20-generic 4.13.8
Uname: Linux 4.13.0-17-generic x86_64
ApportVersion: 2.20.7-0ubuntu3.5
Architecture: amd64
CurrentDesktop: KDE
Date: Wed Nov 29 11:51:05 2017
InstallationDate: Installed on 2017-11-21 (7 days ago)
InstallationMedia: Kubuntu 17.10 "Artful Aardvark" - Release amd64 (20171017.1)
SourcePackage: plasma-workspace
UpgradeStatus: No upgrade log present (probably fresh install)