Поля поиска медленно реагируют на ввод на рабочем столе Plasma KDE

Я использую обновленную версию Kubuntu, с 16.04 по 17.04, а затем до 17.10.

При попытке ввести что-либо в krunner или в поле поиска в меню приложения - буквы просто не отображаются напечатанными.

Иногда буквы появляются после ввода их несколько раз.
Но ни Konsole, ни Browser, ни даже текстовые редакторы не затрагиваются, только поля поиска в krunner и меню приложения.

Обновление : Через некоторое время (и несколько обновлений) начали неправильно работать другие поля ввода:

• поле ввода пароля в сетевом менеджере
• поиск в приложении запуска

Сведения о системе:

Lenovo X1 Carbon Gen 3

Вывод qtdiag:

Qt 5.9.1 (x86_64-little_endian-lp64 shared (dynamic) release build; by GCC 7.2.0) on "xcb" 
OS: Ubuntu 17.10 [linux version 4.13.0-32-generic]

Architecture: x86_64; features: SSE2 SSE3 SSSE3 SSE4.1 SSE4.2 AVX AVX2 RTM HLE

Environment:
  QT4_IM_MODULE="ibus"
  QT_ACCESSIBILITY="1"
  QT_AUTO_SCREEN_SCALE_FACTOR="0"
  QT_IM_MODULE="ibus"
  QT_QPA_PLATFORMTHEME="appmenu-qt5"
  QT_QUICK_CONTROLS_STYLE="org.kde.desktop"

Features: QT_NO_EXCEPTIONS

Library info:
  PrefixPath: /usr
  DocumentationPath: /usr/share/qt5/doc
  HeadersPath: /usr/include/x86_64-linux-gnu/qt5
  LibrariesPath: /usr/lib/x86_64-linux-gnu
  LibraryExecutablesPath: /usr/lib/x86_64-linux-gnu/qt5/libexec
  BinariesPath: /usr/lib/x86_64-linux-gnu/qt5/bin
  PluginsPath: /usr/lib/x86_64-linux-gnu/qt5/plugins
  ImportsPath: /usr/lib/x86_64-linux-gnu/qt5/imports
  Qml2ImportsPath: /usr/lib/x86_64-linux-gnu/qt5/qml
  ArchDataPath: /usr/lib/x86_64-linux-gnu/qt5
  DataPath: /usr/share/qt5
  TranslationsPath: /usr/share/qt5/translations
  ExamplesPath: /usr/lib/x86_64-linux-gnu/qt5/examples
  TestsPath: /usr/tests
  SettingsPath: /etc/xdg

Standard paths [*...* denote writable entry]:
  DesktopLocation: "Desktop" */home/USERNAME/Desktop*
  DocumentsLocation: "Documents" */home/USERNAME/Documents*
  FontsLocation: "Fonts" */home/USERNAME/.local/share/fonts* /home/USERNAME/.fonts
  ApplicationsLocation: "Applications" */home/USERNAME/.local/share/applications* /usr/share/usr/share/xsessions/plasma/applications /usr/local/share/applications /usr/share/applications /var/lib/snapd/desktop/applications
  MusicLocation: "Music" */home/USERNAME/Music*
  MoviesLocation: "Movies" */home/USERNAME/Videos*
  PicturesLocation: "Pictures" */home/USERNAME/Pictures*
  TempLocation: "Temporary Directory" */tmp*
  HomeLocation: "Home" */home/USERNAME*
  AppLocalDataLocation: "Application Data" */home/USERNAME/.local/share/QtProject/qtdiag* /usr/share/usr/share/xsessions/plasma/QtProject/qtdiag /usr/local/share/QtProject/qtdiag /usr/share/QtProject/qtdiag /var/lib/snapd/desktop/QtProject/qtdiag
  CacheLocation: "Cache" */home/USERNAME/.cache/QtProject/qtdiag*
  GenericDataLocation: "Shared Data" */home/USERNAME/.local/share* /usr/share/usr/share/xsessions/plasma /usr/local/share /usr/share /var/lib/snapd/desktop
  RuntimeLocation: "Runtime" */run/user/1000*
  ConfigLocation: "Configuration" */home/USERNAME/.config* /etc/xdg/xdg-/usr/share/xsessions/plasma /etc/xdg/xdg-/usr/share/xsessions/plasma /etc/xdg /usr/share/kubuntu-default-settings/kf5-settings
  DownloadLocation: "Download" */home/USERNAME/Downloads*
  GenericCacheLocation: "Shared Cache" */home/USERNAME/.cache*
  GenericConfigLocation: "Shared Configuration" */home/USERNAME/.config* /etc/xdg/xdg-/usr/share/xsessions/plasma /etc/xdg/xdg-/usr/share/xsessions/plasma /etc/xdg /usr/share/kubuntu-default-settings/kf5-settings
  AppDataLocation: "Application Data" */home/USERNAME/.local/share/QtProject/qtdiag* /usr/share/usr/share/xsessions/plasma/QtProject/qtdiag /usr/local/share/QtProject/qtdiag /usr/share/QtProject/qtdiag /var/lib/snapd/desktop/QtProject/qtdiag
  AppConfigLocation: "Application Configuration" */home/USERNAME/.config/QtProject/qtdiag* /etc/xdg/xdg-/usr/share/xsessions/plasma/QtProject/qtdiag /etc/xdg/xdg-/usr/share/xsessions/plasma/QtProject/qtdiag /etc/xdg/QtProject/qtdiag /usr/share/kubuntu-default-settings/kf5-settings/QtProject/qtdiag

File selectors (increasing order of precedence):
  en_US unix linux ubuntu

Network:
  Using "OpenSSL 1.0.2g  1 Mar 2016", version: 0x1000207f

Platform capabilities: ThreadedPixmaps OpenGL WindowMasks MultipleWindows ForeignWindows NonFullScreenWindows NativeWidgets WindowManagement SyncState RasterGLSurface SwitchableWidgetComposition

Style hints:
  mouseDoubleClickInterval: 300
  mousePressAndHoldInterval: 800
  startDragDistance: 4
  startDragTime: 300
  startDragVelocity: 0
  keyboardInputInterval: 400
  keyboardAutoRepeatRate: 30
  cursorFlashTime: 1000
  showIsFullScreen: 0
  showIsMaximized: 0
  passwordMaskDelay: 0
  passwordMaskCharacter: U+25CF
  fontSmoothingGamma: 1.7
  useRtlExtensions: 0
  setFocusOnTouchRelease: 0
  tabFocusBehavior: Qt::TabFocusBehavior(TabFocusAllControls) 
  singleClickActivation: 0

Additional style hints (QPlatformIntegration):
  ReplayMousePressOutsidePopup: 0

Theme:
  Platforms requested : kde,generic
            available : kde,gtk3
  Styles requested    : oxygen,breeze,fusion,windows
         available    : Breeze,Oxygen,Windows,Fusion
  Icon theme          : breeze, hicolor from /home/USERNAME/.icons,/usr/share/icons
  System font         : "Noto Sans" 12

Fonts:
  General font : "Noto Sans" 12
  Fixed font   : "Hack" 9
  Title font   : "Noto Sans" 12
  Smallest font: "Noto Sans" 8

Palette:
  WindowText: #ff31363b
  Button: #ffeff0f1
  Light: #ffffffff
  Midlight: #fff7f7f8
  Dark: #ff888e93
  Mid: #ffc4c9cd
  Text: #ff31363b
  BrightText: #ffffffff
  ButtonText: #ff31363b
  Base: #fffcfcfc
  Window: #ffeff0f1
  Shadow: #ff474a4c
  Highlight: #ff3daee9
  HighlightedText: #ffeff0f1
  Link: #ff2980b9
  LinkVisited: #ff7f8c8d
  AlternateBase: #ffeff0f1
  NoRole: #ff000000
  ToolTipBase: #ff31363b
  ToolTipText: #ffeff0f1

Screens: 1, High DPI scaling: inactive
# 0 "eDP-1" Depth: 24 Primary: yes
  Manufacturer: 
  Model: 
  Serial number: 
  Geometry: 2560x1440+0+0 Available: 2560x1384+0+0
  Physical size: 310x170 mm  Refresh: 59 Hz Power state: 0
  Physical DPI: 209.755,215.153 Logical DPI: 120,120 Subpixel_None
  DevicePixelRatio: 1 Pixel density: 2
  Primary orientation: 2 Orientation: 2 Native orientation: 0 OrientationUpdateMask: 0

Touch devices: 1
  TouchPad "SynPS/2 Synaptics TouchPad", max 1 touch points, capabilities: Pressure MouseEmulation


LibGL Vendor: Intel Open Source Technology Center
Renderer: Mesa DRI Intel(R) HD Graphics 520 (Skylake GT2) 
Version: 3.0 Mesa 17.2.8
Shading language: 1.30
Format: Version: 3.0 Profile: 0 Swap behavior: 0 Buffer size (RGB): 8,8,8