diff --git a/faststack/app.py b/faststack/app.py
index 375dc78..fda5ad9 100644
--- a/faststack/app.py
+++ b/faststack/app.py
@@ -635,7 +635,10 @@ def apply_filter(self, filter_string: str, filter_flags: list):
 
         if self._is_grid_view_active and self._thumbnail_model:
             self._grid_refreshes += 1
-            self._thumbnail_model.refresh_from_controller(self.image_files)
+            self._thumbnail_model.refresh_from_controller(
+                self.image_files,
+                metadata_map_fn=self._get_bulk_metadata_map,
+            )
             self._path_resolver.update_from_model(self._thumbnail_model)
             self._grid_model_dirty = False
         else:
@@ -683,7 +686,10 @@ def clear_filter(self):
 
         if self._is_grid_view_active and self._thumbnail_model:
             self._grid_refreshes += 1
-            self._thumbnail_model.refresh_from_controller(self.image_files)
+            self._thumbnail_model.refresh_from_controller(
+                self.image_files,
+                metadata_map_fn=self._get_bulk_metadata_map,
+            )
             self._path_resolver.update_from_model(self._thumbnail_model)
             self._grid_model_dirty = False
         else:
@@ -790,7 +796,10 @@ def set_sort_mode(self, mode: str):
 
         if self._is_grid_view_active and self._thumbnail_model:
             self._grid_refreshes += 1
-            self._thumbnail_model.refresh_from_controller(self.image_files)
+            self._thumbnail_model.refresh_from_controller(
+                self.image_files,
+                metadata_map_fn=self._get_bulk_metadata_map,
+            )
             self._path_resolver.update_from_model(self._thumbnail_model)
             self._grid_model_dirty = False
         else:
@@ -1139,7 +1148,10 @@ def load(self, skip_thumbnail_refresh: bool = False):
                 and self._thumbnail_model.rowCount() == 0
             ):
                 self._grid_refreshes += 1
-                self._thumbnail_model.refresh_from_controller(self.image_files)
+                self._thumbnail_model.refresh_from_controller(
+                    self.image_files,
+                    metadata_map_fn=self._get_bulk_metadata_map,
+                )
                 self._path_resolver.update_from_model(self._thumbnail_model)
                 self._grid_model_dirty = False
 
@@ -1218,7 +1230,10 @@ def refresh_image_list(self):
         # Refresh thumbnail model if it exists (for external file changes or startup)
         if self._thumbnail_model and self._is_grid_view_active:
             self._grid_refreshes += 1
-            self._thumbnail_model.refresh_from_controller(self.image_files)
+            self._thumbnail_model.refresh_from_controller(
+                self.image_files,
+                metadata_map_fn=self._get_bulk_metadata_map,
+            )
             self._path_resolver.update_from_model(self._thumbnail_model)
             self._grid_model_dirty = False
 
@@ -2351,7 +2366,10 @@ def _set_grid_view_active(self, active: bool):
                 self._grid_refreshes += 1
 
                 # Always use controller's list, even if empty.
-                self._thumbnail_model.refresh_from_controller(self.image_files)
+                self._thumbnail_model.refresh_from_controller(
+                    self.image_files,
+                    metadata_map_fn=self._get_bulk_metadata_map,
+                )
 
                 # Update path resolver for the current directory
                 self._path_resolver.update_from_model(self._thumbnail_model)
@@ -2588,11 +2606,14 @@ def _get_metadata_dict(self, image_path: Path | str) -> dict:
                 "todo": False,
             }
 
-    def _get_bulk_metadata_map(self) -> Dict[str, dict]:
-        """Get flattened metadata map for all images (for efficient grid refresh)."""
+    def _get_bulk_metadata_map(self, images=None) -> Dict[str, dict]:
+        """Get flattened metadata map for the given images (defaults to self.image_files).
+
+        Used to avoid per-image sidecar lookups on the UI thread during grid refresh.
+        """
         bulk_map = {}
         try:
-            for img in self.image_files:
+            for img in (images if images is not None else self.image_files):
                 key = self.sidecar.metadata_key_for_path(img.path)
                 meta = self.sidecar.get_metadata(img.path, create=False)
                 if meta is None:
diff --git a/faststack/thumbnail_view/model.py b/faststack/thumbnail_view/model.py
index 926a2d0..6096d71 100644
--- a/faststack/thumbnail_view/model.py
+++ b/faststack/thumbnail_view/model.py
@@ -528,12 +528,19 @@ def remove_rows_by_path(self, paths: List[Path]) -> None:
         )
 
     def refresh_from_controller(
-        self, images: List, metadata_map: Optional[Dict[str, dict]] = None
+        self,
+        images: List,
+        metadata_map: Optional[Dict[str, dict]] = None,
+        metadata_map_fn: Optional[Callable[[List], Dict[str, dict]]] = None,
     ):
         """Refresh images from a pre-loaded list without scanning disk.
 
         Folders are still scanned, but image entries are built from the
         provided objects.
+
+        If ``metadata_map_fn`` is provided and ``metadata_map`` is not,
+        the map is built lazily after filename filtering so we only
+        fetch sidecar metadata for images that will actually be shown.
         """
         self._next_source_reason = "refresh"
         cur, own = QThread.currentThread(), self.thread()
@@ -556,6 +563,11 @@ def refresh_from_controller(
                 needle = self._active_filter.lower()
                 images = [img for img in images if needle in img.path.stem.lower()]
 
+            # Build metadata map lazily, after filename filter, so we
+            # don't do sidecar lookups for images that got filtered out.
+            if metadata_map is None and metadata_map_fn is not None:
+                metadata_map = metadata_map_fn(images)
+
             # Apply active flag filters (AND logic)
             if self._active_filter_flags:
                 flags = self._active_filter_flags