diff --git a/src/calibre/db/backend.py b/src/calibre/db/backend.py
index a636d9d503..86ba120e94 100644
--- a/src/calibre/db/backend.py
+++ b/src/calibre/db/backend.py
@@ -1890,11 +1890,12 @@ class DB:
 
     def iter_extra_files(self, book_id, book_path, formats_field, yield_paths=False, pattern=''):
         known_files = {COVER_FILE_NAME, METADATA_FILE_NAME}
-        for fmt in formats_field.for_book(book_id, default_value=()):
-            fname = formats_field.format_fname(book_id, fmt)
-            fpath = self.format_abspath(book_id, fmt, fname, book_path, do_file_rename=False)
-            if fpath:
-                known_files.add(os.path.basename(fpath))
+        if '/' not in pattern:
+            for fmt in formats_field.for_book(book_id, default_value=()):
+                fname = formats_field.format_fname(book_id, fmt)
+                fpath = self.format_abspath(book_id, fmt, fname, book_path, do_file_rename=False)
+                if fpath:
+                    known_files.add(os.path.basename(fpath))
         full_book_path = os.path.abspath(os.path.join(self.library_path, book_path))
         if pattern:
             from pathlib import Path
@@ -1913,9 +1914,9 @@ class DB:
                 relpath = os.path.relpath(path, full_book_path)
                 relpath = relpath.replace(os.sep, '/')
                 if relpath not in known_files:
-                    mtime = os.path.getmtime(path)
+                    stat = os.stat(path)
                     if yield_paths:
-                        yield relpath, path, mtime
+                        yield relpath, path, stat
                     else:
                         try:
                             src = open(path, 'rb')
@@ -1924,7 +1925,7 @@ class DB:
                                 time.sleep(1)
                             src = open(path, 'rb')
                         with src:
-                            yield relpath, src, mtime
+                            yield relpath, src, stat
 
     def add_extra_file(self, relpath, stream, book_path, replace=True, auto_rename=False):
         bookdir = os.path.join(self.library_path, book_path)
diff --git a/src/calibre/db/backup.py b/src/calibre/db/backup.py
index d6747e74b0..2437d7169d 100644
--- a/src/calibre/db/backup.py
+++ b/src/calibre/db/backup.py
@@ -68,6 +68,7 @@ class MetadataBackup(Thread):
                 if self.stop_running.is_set() or self.db.is_closed:
                     return
                 traceback.print_exc()
+
         try:
             book_id = self.db.get_a_dirtied_book()
             if book_id is None:
diff --git a/src/calibre/db/cache.py b/src/calibre/db/cache.py
index 37802a3387..30a4faaaee 100644
--- a/src/calibre/db/cache.py
+++ b/src/calibre/db/cache.py
@@ -24,7 +24,8 @@ from time import monotonic, sleep, time
 from calibre import as_unicode, detect_ncpus, isbytestring
 from calibre.constants import iswindows, preferred_encoding
 from calibre.customize.ui import (
-    run_plugins_on_import, run_plugins_on_postadd, run_plugins_on_postimport, run_plugins_on_postdelete,
+    run_plugins_on_import, run_plugins_on_postadd, run_plugins_on_postdelete,
+    run_plugins_on_postimport,
 )
 from calibre.db import SPOOL_SIZE, _get_next_series_num_for_list
 from calibre.db.annotations import merge_annotations
@@ -154,6 +155,7 @@ class Cache:
         self.formatter_template_cache = {}
         self.dirtied_cache = {}
         self.link_maps_cache = {}
+        self.extra_files_cache = {}
         self.vls_for_books_cache = None
         self.vls_for_books_lib_in_process = None
         self.vls_cache_lock = Lock()
@@ -273,6 +275,13 @@ class Cache:
         self.vls_for_books_cache = None
         self.vls_for_books_lib_in_process = None
 
+    @write_api
+    def clear_extra_files_cache(self, book_id=None):
+        if book_id is None:
+            self.extra_files_cache = {}
+        else:
+            self.extra_files_cache.pop(book_id, None)
+
     @read_api
     def last_modified(self):
         return self.backend.last_modified()
@@ -291,8 +300,9 @@ class Cache:
             self.format_metadata_cache.clear()
         if search_cache:
             self._clear_search_caches(book_ids)
-        self.clear_link_map_cache(book_ids)
+        self._clear_link_map_cache(book_ids)
 
+    @write_api
     def clear_link_map_cache(self, book_ids=None):
         if book_ids is None:
             self.link_maps_cache = {}
@@ -560,7 +570,6 @@ class Cache:
                     has_more = do_one()
                 except Exception:
                     if self.backend.fts_enabled:
-                        import traceback
                         traceback.print_exc()
                 sleep(self.fts_indexing_sleep_time)
 
@@ -1491,7 +1500,7 @@ class Cache:
             if update_path and do_path_update:
                 self._update_path(dirtied, mark_as_dirtied=False)
             self._mark_as_dirty(dirtied)
-            self.clear_link_map_cache(dirtied)
+            self._clear_link_map_cache(dirtied)
             self.event_dispatcher(EventType.metadata_changed, name, dirtied)
         return dirtied
 
@@ -1507,7 +1516,7 @@ class Cache:
             self.format_metadata_cache.pop(book_id, None)
             if mark_as_dirtied:
                 self._mark_as_dirty(book_ids)
-            self.clear_link_map_cache(book_ids)
+            self._clear_link_map_cache(book_ids)
 
     @read_api
     def get_a_dirtied_book(self):
@@ -1540,7 +1549,6 @@ class Cache:
             except:
                 # This almost certainly means that the book has been deleted while
                 # the backup operation sat in the queue.
-                import traceback
                 traceback.print_exc()
         return mi, sequence
 
@@ -2063,7 +2071,6 @@ class Cache:
                     raw = metadata_to_opf(mi)
                     self.backend.write_backup(path, raw)
                 except Exception:
-                    import traceback
                     traceback.print_exc()
         self.backend.remove_books(path_map, permanent=permanent)
         for field in itervalues(self.fields):
@@ -2187,7 +2194,7 @@ class Cache:
                 for book_id in moved_books:
                     self._set_field(f.index_field.name, {book_id:self._get_next_series_num_for(self._fast_field_for(f, book_id), field=field)})
             self._mark_as_dirty(affected_books)
-            self.clear_link_map_cache(affected_books)
+            self._clear_link_map_cache(affected_books)
         self.event_dispatcher(EventType.items_renamed, field, affected_books, id_map)
         return affected_books, id_map
 
@@ -2207,7 +2214,7 @@ class Cache:
                 self._set_field(field.index_field.name, {bid:1.0 for bid in affected_books})
             else:
                 self._mark_as_dirty(affected_books)
-            self.clear_link_map_cache(affected_books)
+            self._clear_link_map_cache(affected_books)
         self.event_dispatcher(EventType.items_removed, field, affected_books, item_ids)
         return affected_books
 
@@ -2342,7 +2349,7 @@ class Cache:
                 self._set_field('author_sort', val_map)
         if changed_books:
             self._mark_as_dirty(changed_books)
-            self.clear_link_map_cache(changed_books)
+            self._clear_link_map_cache(changed_books)
         return changed_books
 
     @write_api
@@ -2353,7 +2360,7 @@ class Cache:
             changed_books |= self._books_for_field('authors', author_id)
         if changed_books:
             self._mark_as_dirty(changed_books)
-            self.clear_link_map_cache(changed_books)
+            self._clear_link_map_cache(changed_books)
         return changed_books
 
     @read_api
@@ -2453,7 +2460,7 @@ class Cache:
             changed_books |= self._books_for_field(field, id_)
         if changed_books:
             self._mark_as_dirty(changed_books)
-            self.clear_link_map_cache(changed_books)
+            self._clear_link_map_cache(changed_books)
         return changed_books
 
     @read_api
@@ -2577,7 +2584,6 @@ class Cache:
                 if progress is not None:
                     progress(item_name, item_count, total)
             except Exception:
-                import traceback
                 traceback.print_exc()
 
         all_paths = {self._field_for('path', book_id).partition('/')[0] for book_id in self._all_book_ids()}
@@ -2666,7 +2672,6 @@ class Cache:
                     try:
                         plugin.run(self)
                     except Exception:
-                        import traceback
                         traceback.print_exc()
         self._shutdown_fts(stage=2)
         with self.write_lock:
@@ -2966,9 +2971,9 @@ class Cache:
             bp = self.field_for('path', book_id)
             extra_files[book_id] = ef = {}
             if bp:
-                for (relpath, fobj, mtime) in self.backend.iter_extra_files(book_id, bp, self.fields['formats']):
+                for (relpath, fobj, stat_result) in self.backend.iter_extra_files(book_id, bp, self.fields['formats']):
                     key = f'{key_prefix}:{book_id}:.|{relpath}'
-                    with exporter.start_file(key, mtime=mtime) as dest:
+                    with exporter.start_file(key, mtime=stat_result.st_mtime) as dest:
                         shutil.copyfileobj(fobj, dest)
                     ef[relpath] = key
         exporter.set_metadata(library_key, metadata)
@@ -3070,6 +3075,7 @@ class Cache:
         added = {}
         for relpath, stream_or_path in map_of_relpath_to_stream_or_path.items():
             added[relpath] = bool(self.backend.add_extra_file(relpath, stream_or_path, path, replace, auto_rename))
+        self._clear_extra_files_cache(book_id)
         return added
 
     @write_api
@@ -3083,21 +3089,36 @@ class Cache:
                 book_path = self._field_for('path', src_id)
                 if book_path:
                     book_path = book_path.replace('/', os.sep)
-                    for (relpath, file_path, mtime) in self.backend.iter_extra_files(
+                    for (relpath, file_path, stat_result) in self.backend.iter_extra_files(
                             src_id, book_path, self.fields['formats'], yield_paths=True):
                         added.add(self.backend.add_extra_file(relpath, file_path, path, replace=replace, auto_rename=True))
+        self._clear_extra_files_cache(dest_id)
         return added
 
     @read_api
-    def list_extra_files_matching(self, book_id, pattern=''):
-        ' List extra data files matching the specified pattern. Empty pattern matches all. Recursive globbing with ** is supported. '
-        path = self._field_for('path', book_id)
-        ans = {}
-        if path:
-            book_path = path.replace('/', os.sep)
-            for (relpath, file_path, mtime) in self.backend.iter_extra_files(
-                    book_id, book_path, self.fields['formats'], yield_paths=True, pattern=pattern):
-                ans[relpath] = file_path
+    def list_extra_files(self, book_id, use_cache=False, pattern=''):
+        '''
+        Get information about extra files in the book's directory.
+
+        :param book_id: the database book id for the book
+        :param pattern: the pattern of filenames to search for. Empty pattern matches all extra files. Patterns must use / as separator.
+                        Use the DATA_FILE_PATTERN constant to match files inside the data directory.
+
+        :return: A tuple of all extra files matching the specified pattern. Each element of the tuple is (relpath, file_path, stat_result)
+                 where relpath is the relative path of the file to the book directory using / as a separator.
+                 stat_result is the result of calling os.stat() on the file.
+        '''
+        key = book_id, pattern
+        ans = self.extra_files_cache.get(key)
+        if ans is None or not use_cache:
+            ans = []
+            path = self._field_for('path', book_id)
+            if path:
+                for (relpath, file_path, stat_result) in self.backend.iter_extra_files(
+                    book_id, path, self.fields['formats'], yield_paths=True, pattern=pattern
+                ):
+                    ans.append((relpath, file_path, stat_result))
+            self.extra_files_cache[key] = ans = tuple(ans)
         return ans
 
     @read_api
diff --git a/src/calibre/db/cli/cmd_export.py b/src/calibre/db/cli/cmd_export.py
index 20032dd5e4..66e463d290 100644
--- a/src/calibre/db/cli/cmd_export.py
+++ b/src/calibre/db/cli/cmd_export.py
@@ -6,6 +6,7 @@ import os
 
 from calibre.db.cli import integers_from_string
 from calibre.db.errors import NoSuchFormat
+from calibre.db.constants import DATA_FILE_PATTERN
 from calibre.library.save_to_disk import (
     config, do_save_book_to_disk, get_formats, sanitize_args
 )
@@ -26,7 +27,7 @@ def implementation(db, notify_changes, action, *args):
         mi = db.get_metadata(book_id)
         plugboards = db.pref('plugboards', {})
         formats = get_formats(db.formats(book_id), formats)
-        extra_files_for_export = tuple(db.list_extra_files_matching(book_id, 'data/**/*'))
+        extra_files_for_export = tuple(relpath for (relpath, file_path, stat_result) in db.list_extra_files(book_id, pattern=DATA_FILE_PATTERN))
         plugboards['extra_files_for_export'] = extra_files_for_export
         return mi, plugboards, formats, db.library_id, db.pref(
             'user_template_functions', []
diff --git a/src/calibre/db/constants.py b/src/calibre/db/constants.py
index 821027b61b..c443a52b7d 100644
--- a/src/calibre/db/constants.py
+++ b/src/calibre/db/constants.py
@@ -9,6 +9,7 @@ METADATA_FILE_NAME = 'metadata.opf'
 DEFAULT_TRASH_EXPIRY_TIME_SECONDS = 14 * 86400
 TRASH_DIR_NAME =  '.caltrash'
 DATA_DIR_NAME = 'data'
+DATA_FILE_PATTERN = f'{DATA_DIR_NAME}/**/*'
 BOOK_ID_PATH_TEMPLATE = ' ({})'
 
 
diff --git a/src/calibre/db/copy_to_library.py b/src/calibre/db/copy_to_library.py
index e0f7395185..98dbe81d83 100644
--- a/src/calibre/db/copy_to_library.py
+++ b/src/calibre/db/copy_to_library.py
@@ -79,7 +79,9 @@ def copy_one_book(
             mi.timestamp = now()
         format_map = {}
         fmts = list(db.formats(book_id, verify_formats=False))
-        extra_file_map = db.list_extra_files_matching(book_id)
+        extra_file_map = {}
+        for (relpath, file_path, stat_result) in db.list_extra_files(book_id):
+            extra_file_map[relpath] = file_path
         for fmt in fmts:
             path = db.format_abspath(book_id, fmt)
             if path:
@@ -112,7 +114,7 @@ def copy_one_book(
             preserve_uuid=preserve_uuid, run_hooks=False)[0][0]
         bp = db.field_for('path', book_id)
         if bp:
-            for (relpath, src_path, mtime) in db.backend.iter_extra_files(book_id, bp, db.fields['formats'], yield_paths=True):
+            for (relpath, src_path, stat_result) in db.backend.iter_extra_files(book_id, bp, db.fields['formats'], yield_paths=True):
                 nbp = newdb.field_for('path', new_book_id)
                 if nbp:
                     newdb.backend.add_extra_file(relpath, src_path, nbp)
diff --git a/src/calibre/db/tests/add_remove.py b/src/calibre/db/tests/add_remove.py
index ed0325e6f0..636ad8f330 100644
--- a/src/calibre/db/tests/add_remove.py
+++ b/src/calibre/db/tests/add_remove.py
@@ -410,7 +410,7 @@ class AddRemoveTest(BaseTest):
             self.assertFalse(os.path.exists(os.path.join(bookdir, 'sub', 'recurse')))
 
         def clear_extra_files(book_id):
-            for file_path in dest_db.list_extra_files_matching(book_id).values():
+            for (relpath, file_path, stat_result) in dest_db.list_extra_files(book_id):
                 os.remove(file_path)
 
         assert_does_not_have_extra_files(1)
@@ -468,7 +468,7 @@ class AddRemoveTest(BaseTest):
 
         def extra_files_for(book_id):
             ans = {}
-            for relpath, file_path in db.list_extra_files_matching(book_id).items():
+            for relpath, file_path, stat_result in db.list_extra_files(book_id):
                 with open(file_path) as f:
                     ans[relpath] = f.read()
             return ans
diff --git a/src/calibre/db/tests/filesystem.py b/src/calibre/db/tests/filesystem.py
index db55ccac8d..83bf8917cc 100644
--- a/src/calibre/db/tests/filesystem.py
+++ b/src/calibre/db/tests/filesystem.py
@@ -103,6 +103,11 @@ class FilesystemTest(BaseTest):
 
         # test only formats being changed
         init_cache()
+        ef = set()
+        for (relpath, file_path, stat_result) in cache.list_extra_files(1):
+            ef.add(relpath)
+            self.assertTrue(os.path.exists(file_path))
+        self.assertEqual(ef, {'a.side', 'subdir/a.fmt1'})
         fname = cache.fields['formats'].table.fname_map[1]['FMT1']
         cache.fields['formats'].table.fname_map[1]['FMT1'] = 'some thing else'
         cache.fields['formats'].table.fname_map[1]['FMT2'] = fname.upper()
@@ -224,8 +229,8 @@ class FilesystemTest(BaseTest):
         os.mkdir(os.path.join(bookdir, 'sub'))
         with open(os.path.join(bookdir, 'sub', 'recurse'), 'w') as f:
             f.write('recurse')
-        self.assertEqual(set(cache.list_extra_files_matching(1, 'sub/**/*')), {'sub/recurse'})
-        self.assertEqual(set(cache.list_extra_files_matching(1, '')), {'exf', 'sub/recurse'})
+        self.assertEqual({relpath for (relpath, _, _) in cache.list_extra_files(1, pattern='sub/**/*')}, {'sub/recurse'})
+        self.assertEqual({relpath for (relpath, _, _) in cache.list_extra_files(1)}, {'exf', 'sub/recurse'})
         for part_size in (1 << 30, 100, 1):
             with TemporaryDirectory('export_lib') as tdir, TemporaryDirectory('import_lib') as idir:
                 exporter = Exporter(tdir, part_size=part_size)
diff --git a/src/calibre/db/tests/writing.py b/src/calibre/db/tests/writing.py
index ccffb79227..83f839534f 100644
--- a/src/calibre/db/tests/writing.py
+++ b/src/calibre/db/tests/writing.py
@@ -381,7 +381,7 @@ class WritingTest(BaseTest):
         def read_all_extra_files(book_id=1):
             ans = {}
             bp = cache.field_for('path', book_id)
-            for (relpath, fobj, mtime) in cache.backend.iter_extra_files(book_id, bp, cache.fields['formats']):
+            for (relpath, fobj, stat_result) in cache.backend.iter_extra_files(book_id, bp, cache.fields['formats']):
                 ans[relpath] = fobj.read()
             return ans
 
diff --git a/src/calibre/gui2/actions/choose_library.py b/src/calibre/gui2/actions/choose_library.py
index 46f5025eb3..9d9cc6ed5a 100644
--- a/src/calibre/gui2/actions/choose_library.py
+++ b/src/calibre/gui2/actions/choose_library.py
@@ -329,6 +329,10 @@ class ChooseLibraryAction(InterfaceAction):
                                       None, None),
                                       attr='action_restore_database')
         ac.triggered.connect(self.restore_database, type=Qt.ConnectionType.QueuedConnection)
+        ac = self.create_action(spec=(_('Clear extra files cache'), 'lt.png',
+                                      None, None),
+                                      attr='action_clear_extra_files_cache')
+        ac.triggered.connect(self.clear_extra_files_cache, type=Qt.ConnectionType.QueuedConnection)
         self.maintenance_menu.addAction(ac)
 
         self.choose_menu.addMenu(self.maintenance_menu)
@@ -649,6 +653,10 @@ class ChooseLibraryAction(InterfaceAction):
         if restore_database(db, self.gui):
             self.gui.library_moved(db.library_path)
 
+    def clear_extra_files_cache(self):
+        db = self.gui.library_view.model().db
+        db.new_api.clear_extra_files_cache()
+
     def check_library(self):
         from calibre.gui2.dialogs.check_library import CheckLibraryDialog, DBCheck
         self.gui.library_view.save_state()
diff --git a/src/calibre/gui2/actions/view.py b/src/calibre/gui2/actions/view.py
index 2c74390189..b1986854b9 100644
--- a/src/calibre/gui2/actions/view.py
+++ b/src/calibre/gui2/actions/view.py
@@ -273,7 +273,9 @@ class ViewAction(InterfaceAction):
         if not self._view_check(len(rows), max_=10, skip_dialog_name='open-folder-many-check'):
             return
         for i, row in enumerate(rows):
-            path = self.gui.library_view.model().db.abspath(row.row())
+            db = self.gui.library_view.model().db
+            db.new_api.clear_extra_files_cache(self.gui.library_view.model().id(row))
+            path = db.abspath(row.row())
             open_local_file(path)
             if ismacos and i < len(rows) - 1:
                 time.sleep(0.1)  # Finder cannot handle multiple folder opens
@@ -283,7 +285,9 @@ class ViewAction(InterfaceAction):
         open_local_file(path)
 
     def view_data_folder_for_id(self, id_):
-        path = self.gui.library_view.model().db.abspath(id_, index_is_id=True)
+        db = self.gui.library_view.model().db
+        db.new_api.clear_extra_files_cache(id_)
+        path = db.abspath(id_, index_is_id=True)
         open_local_file(os.path.join(path, DATA_DIR_NAME))
 
     def view_book(self, triggered):
diff --git a/src/calibre/gui2/save.py b/src/calibre/gui2/save.py
index 9976a42a5e..83c512f764 100644
--- a/src/calibre/gui2/save.py
+++ b/src/calibre/gui2/save.py
@@ -16,6 +16,7 @@ from calibre import force_unicode, prints
 from calibre.constants import DEBUG
 from calibre.customize.ui import can_set_metadata
 from calibre.db.errors import NoSuchFormat
+from calibre.db.constants import DATA_FILE_PATTERN
 from calibre.ebooks.metadata import authors_to_string
 from calibre.ebooks.metadata.opf2 import metadata_to_opf
 from calibre.gui2 import error_dialog, gprefs, open_local_file, warning_dialog
@@ -213,7 +214,9 @@ class Saver(QObject):
 
         extra_files = {}
         if self.opts.save_extra_files:
-            extra_files = self.db.new_api.list_extra_files_matching(int(book_id), 'data/**/*')
+            extra_files = {}
+            for (relpath, file_path, stat_result) in self.db.new_api.list_extra_files(int(book_id), pattern=DATA_FILE_PATTERN):
+                extra_files[relpath] = file_path
         if not fmts and not self.opts.write_opf and not self.opts.save_cover and not extra_files:
             return