diff --git a/src/calibre/gui2/__init__.py b/src/calibre/gui2/__init__.py
index 4ee96eb52b..5b7cc484fe 100644
--- a/src/calibre/gui2/__init__.py
+++ b/src/calibre/gui2/__init__.py
@@ -9,6 +9,7 @@ import signal
 import sys
 import threading
 from contextlib import contextmanager
+from functools import lru_cache
 from qt.core import (
     QT_VERSION, QApplication, QBuffer, QByteArray, QColor, QDateTime,
     QDesktopServices, QDialog, QDialogButtonBox, QEvent, QFileDialog,
@@ -1126,7 +1127,19 @@ class Application(QApplication):
         QTimer.singleShot(1000, lambda: QApplication.instance().setAttribute(Qt.ApplicationAttribute.AA_SetPalette, False))
         self.ignore_palette_changes = False
 
+    @lru_cache(maxsize=256)
+    def cached_qimage(self, name):
+        return self.cached_qpixmap(name).toImage()
+
+    @lru_cache(maxsize=256)
+    def cached_qpixmap(self, name):
+        ic = QIcon.ic(name)
+        pmap = ic.pixmap(ic.availableSizes()[0])
+        return pmap
+
     def on_palette_change(self):
+        self.cached_qimage.cache_clear()
+        self.cached_qpixmap.cache_clear()
         self.is_dark_theme = is_dark_theme()
         self.setProperty('is_dark_theme', self.is_dark_theme)
         if self.using_calibre_style:
diff --git a/src/calibre/gui2/actions/device.py b/src/calibre/gui2/actions/device.py
index 15056d4b3f..665c9b91c5 100644
--- a/src/calibre/gui2/actions/device.py
+++ b/src/calibre/gui2/actions/device.py
@@ -126,9 +126,9 @@ class ShareConnMenu(QMenu):  # {{{
                 subject = opts.subjects.get(account, '')
                 alias = opts.aliases.get(account, '')
                 dest = 'mail:'+account+';'+formats+';'+subject
-                action1 = DeviceAction(dest, False, False, I('mail.png'),
+                action1 = DeviceAction(dest, False, False, 'mail.png',
                         alias or account)
-                action2 = DeviceAction(dest, True, False, I('mail.png'),
+                action2 = DeviceAction(dest, True, False, 'mail.png',
                         (alias or account) + ' ' + _('(delete from library)'))
                 self.email_to_menu.addAction(action1)
                 self.email_to_and_delete_menu.addAction(action2)
@@ -136,22 +136,22 @@ class ShareConnMenu(QMenu):  # {{{
                 self.memory.append(action2)
                 if default:
                     ac = DeviceAction(dest, False, False,
-                            I('mail.png'), _('Email to') + ' ' +(alias or
+                            'mail.png', _('Email to') + ' ' +(alias or
                                 account))
                     self.addAction(ac)
                     self.email_actions.append(ac)
                     ac.a_s.connect(sync_menu.action_triggered)
                 action1.a_s.connect(sync_menu.action_triggered)
                 action2.a_s.connect(sync_menu.action_triggered)
-            action1 = DeviceAction('choosemail:', False, False, I('mail.png'),
+            action1 = DeviceAction('choosemail:', False, False, 'mail.png',
                     _('Select recipients'))
-            action2 = DeviceAction('choosemail:', True, False, I('mail.png'),
+            action2 = DeviceAction('choosemail:', True, False, 'mail.png',
                     _('Select recipients') + ' ' + _('(delete from library)'))
             self.email_to_menu.addAction(action1)
             self.email_to_and_delete_menu.addAction(action2)
             self.memory.append(action1)
             self.memory.append(action2)
-            tac1 = DeviceAction('choosemail:', False, False, I('mail.png'),
+            tac1 = DeviceAction('choosemail:', False, False, 'mail.png',
                     _('Email to selected recipients...'))
             self.addAction(tac1)
             tac1.a_s.connect(sync_menu.action_triggered)
diff --git a/src/calibre/gui2/actions/edit_metadata.py b/src/calibre/gui2/actions/edit_metadata.py
index bc604052ca..af8e178626 100644
--- a/src/calibre/gui2/actions/edit_metadata.py
+++ b/src/calibre/gui2/actions/edit_metadata.py
@@ -379,7 +379,7 @@ class EditMetadataAction(InterfaceAction):
                 intro_msg=_('The downloaded metadata is on the left and the original metadata'
                             ' is on the right. If a downloaded value is blank or unknown,'
                             ' the original value is used.'),
-                action_button=(_('&View book'), I('view.png'), self.gui.iactions['View'].view_historical),
+                action_button=(_('&View book'), 'view.png', self.gui.iactions['View'].view_historical),
                 db=db
             )
             if d.exec() == QDialog.DialogCode.Accepted:
diff --git a/src/calibre/gui2/actions/store.py b/src/calibre/gui2/actions/store.py
index c9f6279bde..69ea2ffc8b 100644
--- a/src/calibre/gui2/actions/store.py
+++ b/src/calibre/gui2/actions/store.py
@@ -4,7 +4,7 @@ __docformat__ = 'restructuredtext en'
 
 from functools import partial
 
-from qt.core import QIcon, QSize
+from qt.core import QIcon
 
 from calibre.gui2 import error_dialog
 from calibre.gui2.actions import InterfaceAction
@@ -37,8 +37,7 @@ class StoreAction(InterfaceAction):
 
     def load_menu(self):
         self.store_list_menu.clear()
-        icon = QIcon()
-        icon.addFile(I('donate.png'), QSize(16, 16))
+        icon = QIcon.ic('donate.png')
         for n, p in sorted(self.gui.istores.items(), key=lambda x: x[0].lower()):
             if p.base_plugin.affiliate:
                 self.store_list_menu.addAction(icon, n,
diff --git a/src/calibre/gui2/book_details.py b/src/calibre/gui2/book_details.py
index 56a22f5a0a..2750e7f1d7 100644
--- a/src/calibre/gui2/book_details.py
+++ b/src/calibre/gui2/book_details.py
@@ -516,7 +516,7 @@ class CoverView(QWidget):  # {{{
                 QSizePolicy.Policy.Expanding if vertical else QSizePolicy.Policy.Minimum,
                 QSizePolicy.Policy.Expanding)
 
-        self.default_pixmap = QPixmap(I('default_cover.png'))
+        self.default_pixmap = QApplication.instance().cached_qpixmap('default_cover.png')
         self.pixmap = self.default_pixmap
         self.pwidth = self.pheight = None
         self.data = {}
diff --git a/src/calibre/gui2/convert/debug.py b/src/calibre/gui2/convert/debug.py
index aa3efc4d8e..e61e93bd2f 100644
--- a/src/calibre/gui2/convert/debug.py
+++ b/src/calibre/gui2/convert/debug.py
@@ -16,7 +16,7 @@ from calibre.ebooks.conversion.config import OPTIONS
 class DebugWidget(Widget, Ui_Form):
 
     TITLE = _('Debug')
-    ICON  = I('debug.png')
+    ICON  = 'debug.png'
     HELP  = _('Debug the conversion process.')
     COMMIT_NAME = 'debug'
 
diff --git a/src/calibre/gui2/convert/look_and_feel.py b/src/calibre/gui2/convert/look_and_feel.py
index 4c7e01627e..0fcd6e6d3e 100644
--- a/src/calibre/gui2/convert/look_and_feel.py
+++ b/src/calibre/gui2/convert/look_and_feel.py
@@ -18,7 +18,7 @@ from polyglot.builtins import iteritems
 class LookAndFeelWidget(Widget, Ui_Form):
 
     TITLE = _('Look & feel')
-    ICON  = I('lookfeel.png')
+    ICON  = 'lookfeel.png'
     HELP  = _('Control the look and feel of the output.')
     COMMIT_NAME = 'look_and_feel'
 
diff --git a/src/calibre/gui2/convert/metadata.py b/src/calibre/gui2/convert/metadata.py
index 447b0a0e56..71b82a14d6 100644
--- a/src/calibre/gui2/convert/metadata.py
+++ b/src/calibre/gui2/convert/metadata.py
@@ -7,7 +7,7 @@ __docformat__ = 'restructuredtext en'
 
 import os, re, errno
 
-from qt.core import QPixmap
+from qt.core import QPixmap, QApplication
 
 from calibre.gui2 import choose_images, error_dialog
 from calibre.gui2.convert.metadata_ui import Ui_Form
@@ -49,7 +49,7 @@ def create_cover_file(db, book_id):
 class MetadataWidget(Widget, Ui_Form):
 
     TITLE = _('Metadata')
-    ICON  = I('dialog_information.png')
+    ICON  = 'dialog_information.png'
     HELP  = _('Set the metadata. The output file will contain as much of this '
             'metadata as possible.')
     COMMIT_NAME = 'metadata'
@@ -111,8 +111,7 @@ class MetadataWidget(Widget, Ui_Form):
                 self.cover_data = cover
                 self.set_cover_tooltip(pm)
         else:
-            pm = QPixmap(I('default_cover.png'))
-            pm.setDevicePixelRatio(getattr(self, 'devicePixelRatioF', self.devicePixelRatio)())
+            pm = QApplication.instance().cached_qpixmap('default_cover.png')
             self.cover.setPixmap(pm)
             self.cover.setToolTip(_('This book has no cover'))
         for x in ('author', 'series', 'publisher'):
diff --git a/src/calibre/gui2/convert/structure_detection.py b/src/calibre/gui2/convert/structure_detection.py
index f1826faaf0..56a1901fe4 100644
--- a/src/calibre/gui2/convert/structure_detection.py
+++ b/src/calibre/gui2/convert/structure_detection.py
@@ -14,7 +14,7 @@ from calibre.ebooks.conversion.config import OPTIONS
 class StructureDetectionWidget(Widget, Ui_Form):
 
     TITLE = _('Structure\ndetection')
-    ICON  = I('chapters.png')
+    ICON  = 'chapters.png'
     HELP  = _('Fine tune the detection of chapter headings and '
             'other document structure.')
     COMMIT_NAME = 'structure_detection'
diff --git a/src/calibre/gui2/convert/toc.py b/src/calibre/gui2/convert/toc.py
index e7677f075f..719f6b9d02 100644
--- a/src/calibre/gui2/convert/toc.py
+++ b/src/calibre/gui2/convert/toc.py
@@ -16,7 +16,7 @@ from calibre.ebooks.conversion.config import OPTIONS
 class TOCWidget(Widget, Ui_Form):
 
     TITLE = _('Table of\nContents')
-    ICON  = I('toc.png')
+    ICON  = 'toc.png'
     HELP  = _('Control the creation/conversion of the Table of Contents.')
     COMMIT_NAME = 'toc'
 
diff --git a/src/calibre/gui2/dialogs/confirm_delete_location.py b/src/calibre/gui2/dialogs/confirm_delete_location.py
index 58b9f49df6..98111edebb 100644
--- a/src/calibre/gui2/dialogs/confirm_delete_location.py
+++ b/src/calibre/gui2/dialogs/confirm_delete_location.py
@@ -7,7 +7,7 @@ __copyright__ = '2008, Kovid Goyal kovid@kovidgoyal.net' \
 __docformat__ = 'restructuredtext en'
 
 from calibre.gui2.dialogs.confirm_delete_location_ui import Ui_Dialog
-from qt.core import QDialog, Qt, QPixmap, QIcon
+from qt.core import QDialog, Qt, QIcon
 
 
 class Dialog(QDialog, Ui_Dialog):
@@ -42,8 +42,9 @@ class Dialog(QDialog, Ui_Dialog):
 
 def confirm_location(msg, name, parent=None, pixmap='dialog_warning.png'):
     d = Dialog(msg, name, parent)
-    d.label.setPixmap(QPixmap(I(pixmap)))
-    d.setWindowIcon(QIcon.ic(pixmap))
+    ic = QIcon.ic(pixmap)
+    d.label.setPixmap(ic.pixmap(ic.availableSizes()[0]))
+    d.setWindowIcon(ic)
     d.resize(d.sizeHint())
     ret = d.exec()
     d.break_cycles()
diff --git a/src/calibre/gui2/dialogs/plugin_updater.py b/src/calibre/gui2/dialogs/plugin_updater.py
index 780cce6b79..aa82ee213a 100644
--- a/src/calibre/gui2/dialogs/plugin_updater.py
+++ b/src/calibre/gui2/dialogs/plugin_updater.py
@@ -11,8 +11,7 @@ import traceback
 from qt.core import (
     QAbstractItemView, QAbstractTableModel, QAction, QApplication, QBrush, QComboBox,
     QDialog, QDialogButtonBox, QFont, QFrame, QHBoxLayout, QIcon, QLabel, QLineEdit,
-    QModelIndex, QPixmap, QSize, QSortFilterProxyModel, Qt, QTableView, QUrl,
-    QVBoxLayout
+    QModelIndex, QSize, QSortFilterProxyModel, Qt, QTableView, QUrl, QVBoxLayout
 )
 
 from calibre import prints
@@ -129,13 +128,12 @@ class ImageTitleLayout(QHBoxLayout):
         title_font = QFont()
         title_font.setPointSize(16)
         title_image_label = QLabel(parent)
-        pixmap = QPixmap()
-        pixmap.load(I(icon_name))
-        if pixmap is None:
+        ic = QIcon.ic(icon_name)
+        if ic.isNull():
             error_dialog(parent, _('Restart required'),
                          _('You must restart calibre before using this plugin!'), show=True)
         else:
-            title_image_label.setPixmap(pixmap)
+            title_image_label.setPixmap(ic.pixmap(32, 32))
         title_image_label.setMaximumSize(32, 32)
         title_image_label.setScaledContents(True)
         self.addWidget(title_image_label)
@@ -387,7 +385,7 @@ class DisplayPluginModel(QAbstractTableModel):
                 icon_name = 'plugin_new_valid.png'
             else:
                 icon_name = 'plugin_new_invalid.png'
-        return QIcon(I('plugins/' + icon_name))
+        return QIcon.ic('plugins/' + icon_name)
 
     def _get_status_tooltip(self, display_plugin):
         if display_plugin.is_deprecated:
diff --git a/src/calibre/gui2/init.py b/src/calibre/gui2/init.py
index 52db152397..0e95fe8161 100644
--- a/src/calibre/gui2/init.py
+++ b/src/calibre/gui2/init.py
@@ -153,7 +153,7 @@ class LibraryWidget(Splitter):  # {{{
         idx = 0 if orientation == Qt.Orientation.Vertical else 1
         size = 300 if orientation == Qt.Orientation.Vertical else 550
         Splitter.__init__(self, 'cover_browser_splitter', _('Cover browser'),
-                I('cover_flow.png'),
+                'cover_flow.png',
                 orientation=orientation, parent=parent,
                 connect_button=not config['separate_cover_flow'],
                 side_index=idx, initial_side_size=size, initial_show=False,
diff --git a/src/calibre/gui2/library/models.py b/src/calibre/gui2/library/models.py
index 1577539f71..1b1e8af84f 100644
--- a/src/calibre/gui2/library/models.py
+++ b/src/calibre/gui2/library/models.py
@@ -47,8 +47,6 @@ TIME_FMT = '%d %b %Y'
 ALIGNMENT_MAP = {'left': Qt.AlignmentFlag.AlignLeft, 'right': Qt.AlignmentFlag.AlignRight, 'center':
         Qt.AlignmentFlag.AlignHCenter}
 
-_default_image = None
-
 
 def render_pin(color='green', save_to=None):
     svg = P('pin-template.svg', data=True).replace(b'fill:#f39509', ('fill:' + color).encode('utf-8'))
@@ -61,13 +59,6 @@ def render_pin(color='green', save_to=None):
     return pm
 
 
-def default_image():
-    global _default_image
-    if _default_image is None:
-        _default_image = QImage(I('default_cover.png'))
-    return _default_image
-
-
 def group_numbers(numbers):
     for k, g in groupby(enumerate(sorted(numbers)), lambda i_x:i_x[0] - i_x[1]):
         first = None
@@ -224,7 +215,6 @@ class BooksModel(QAbstractTableModel):  # {{{
         self.editable_cols = ['title', 'authors', 'rating', 'publisher',
                               'tags', 'series', 'timestamp', 'pubdate',
                               'languages']
-        self.default_image = default_image()
         self.sorted_on = DEFAULT_SORT
         self.sort_history = [self.sorted_on]
         self.last_search = ''  # The last search performed on this model
@@ -276,6 +266,10 @@ class BooksModel(QAbstractTableModel):  # {{{
         self.marked_text_icons[label] = color, ans
         return ans
 
+    @property
+    def default_image(self):
+        return QApplication.instance().cached_qimage('default_cover.png')
+
     def _clear_caches(self):
         self.color_cache = defaultdict(dict)
         self.icon_cache = defaultdict(dict)
diff --git a/src/calibre/gui2/main.py b/src/calibre/gui2/main.py
index 367ca93feb..288d36e3ec 100644
--- a/src/calibre/gui2/main.py
+++ b/src/calibre/gui2/main.py
@@ -132,7 +132,7 @@ def init_qt(args):
     # Ancient broken VNC servers cannot handle icons of size greater than 256
     # https://www.mobileread.com/forums/showthread.php?t=278447
     ic = 'lt.png' if is_x11 else 'library.png'
-    app.setWindowIcon(QIcon(I(ic, allow_user_override=False)))
+    app.setWindowIcon(QIcon.ic(ic))
     return app, opts, args
 
 
diff --git a/src/calibre/gui2/metadata/basic_widgets.py b/src/calibre/gui2/metadata/basic_widgets.py
index 82d645ac8e..9f90268ae8 100644
--- a/src/calibre/gui2/metadata/basic_widgets.py
+++ b/src/calibre/gui2/metadata/basic_widgets.py
@@ -1285,7 +1285,7 @@ class Cover(ImageView):  # {{{
         if cdata:
             pm.loadFromData(cdata)
         if pm.isNull():
-            pm = QPixmap(I('default_cover.png'))
+            pm = QApplication.instance().cached_qpixmap('default_cover.png')
         else:
             self._cdata = cdata
         pm.setDevicePixelRatio(getattr(self, 'devicePixelRatioF', self.devicePixelRatio)())
diff --git a/src/calibre/gui2/metadata/diff.py b/src/calibre/gui2/metadata/diff.py
index b5e9487bd3..4baece3486 100644
--- a/src/calibre/gui2/metadata/diff.py
+++ b/src/calibre/gui2/metadata/diff.py
@@ -318,7 +318,8 @@ class CoverView(QWidget):
         self.field = field
         self.metadata = metadata
         self.pixmap = None
-        self.blank = QPixmap(I('blank.png'))
+        ic = QIcon.ic('blank.png')
+        self.blank = ic.pixmap(ic.availableSizes()[0])
         self.setSizePolicy(QSizePolicy.Policy.Preferred, QSizePolicy.Policy.MinimumExpanding)
         self.sizePolicy().setHeightForWidth(True)
 
@@ -665,7 +666,7 @@ class CompareMany(QDialog):
             self.addAction(ac)
         if action_button is not None:
             self.acb = b = bb.addButton(action_button[0], QDialogButtonBox.ButtonRole.ActionRole)
-            b.setIcon(QIcon(action_button[1]))
+            b.setIcon(QIcon.ic(action_button[1]))
             self.action_button_action = action_button[2]
             b.clicked.connect(self.action_button_clicked)
         self.nb = b = bb.addButton(_('&Next') if self.total > 1 else _('&OK'), QDialogButtonBox.ButtonRole.ActionRole)
diff --git a/src/calibre/gui2/metadata/single_download.py b/src/calibre/gui2/metadata/single_download.py
index 32f4d1bc20..2d941cdb12 100644
--- a/src/calibre/gui2/metadata/single_download.py
+++ b/src/calibre/gui2/metadata/single_download.py
@@ -622,7 +622,8 @@ class CoversModel(QAbstractListModel):  # {{{
         QAbstractListModel.__init__(self, parent)
 
         if current_cover is None:
-            current_cover = QPixmap(I('default_cover.png'))
+            ic = QIcon.ic('default_cover.png')
+            current_cover = ic.pixmap(ic.availableSizes()[0])
         current_cover.setDevicePixelRatio(QApplication.instance().devicePixelRatio())
 
         self.blank = QIcon.ic('blank.png').pixmap(*CoverDelegate.ICON_SIZE)
diff --git a/src/calibre/gui2/widgets.py b/src/calibre/gui2/widgets.py
index e17a4eedc4..0a84eb9ee2 100644
--- a/src/calibre/gui2/widgets.py
+++ b/src/calibre/gui2/widgets.py
@@ -1097,7 +1097,7 @@ class Splitter(QSplitter):
             self.button.clicked.connect(self.double_clicked)
 
         if shortcut is not None:
-            self.action_toggle = QAction(QIcon(icon), _('Toggle') + ' ' + label,
+            self.action_toggle = QAction(QIcon.ic(icon), _('Toggle') + ' ' + label,
                     self)
             self.action_toggle.changed.connect(self.update_shortcut)
             self.action_toggle.triggered.connect(self.toggle_triggered)