diff --git a/src/textual/_arrange.py b/src/textual/_arrange.py
index 2bf706e0f..102c17844 100644
--- a/src/textual/_arrange.py
+++ b/src/textual/_arrange.py
@@ -50,7 +50,7 @@ def arrange(
     get_dock = attrgetter("styles.dock")
     styles = widget.styles
 
-    for widgets in dock_layers.values():
+    for index, widgets in enumerate(dock_layers.values()):
 
         layout_widgets, dock_widgets = partition(get_dock, widgets)
 
diff --git a/src/textual/_compositor.py b/src/textual/_compositor.py
index 75dc2a51f..689e5b93c 100644
--- a/src/textual/_compositor.py
+++ b/src/textual/_compositor.py
@@ -388,16 +388,16 @@ class Compositor:
                         spatial_map.total_region.grow(spacing)
                     )
 
-                    placements = spatial_map.get_placements(
-                        child_region.reset_offset.translate(widget.scroll_offset)
-                    )
-
                     widgets.update(arranged_widgets)
 
                     # An offset added to all placements
                     placement_offset = container_region.offset + layout_offset
                     placement_scroll_offset = placement_offset - widget.scroll_offset
 
+                    placements = spatial_map.get_placements(
+                        (child_region.size.region).translate(widget.scroll_offset)
+                    )
+
                     _layers = widget.layers
                     layers_to_index = {
                         layer_name: index for index, layer_name in enumerate(_layers)
diff --git a/src/textual/_spatial_map.py b/src/textual/_spatial_map.py
index eb2685554..8f5d9879e 100644
--- a/src/textual/_spatial_map.py
+++ b/src/textual/_spatial_map.py
@@ -8,6 +8,7 @@ from typing import Iterable, Sequence
 from ._layout import WidgetPlacement
 from .geometry import Region, Spacing
 from ._partition import partition
+from ._profile import timer
 
 
 class SpatialMap:
@@ -27,8 +28,8 @@ class SpatialMap:
         self,
         placements: Sequence[WidgetPlacement],
         *,
-        block_width: int = 80,
-        block_height: int = 80,
+        block_width: int = 40,
+        block_height: int = 20,
     ) -> None:
         self._placements = placements
         self._total_region = Region()
@@ -39,8 +40,6 @@ class SpatialMap:
 
         self.placement_map = self._build_placements(placements)
 
-        print("SPATIAL", len(placements))
-
     def __iter__(self) -> Iterable[WidgetPlacement]:
         yield from self._placements
 
@@ -92,17 +91,24 @@ class SpatialMap:
         Returns:
             Iterable[WidgetPlacement]: A super-set of Widget placements that may be in the screen.
         """
+        return [
+            placement
+            for placement in self._placements
+            if screen_region.overlaps(placement.region)
+        ]
         x1, y1, width, height = screen_region
         x2 = x1 + width
         y2 = y1 + height
         block_width = self._block_width
         block_height = self._block_height
 
-        placements: set[WidgetPlacement] = set(self._fixed)
+        placements: set[WidgetPlacement] = set()
         extend_placements = placements.update
         map = self.placement_map
         map_get = map.get
 
+        overlaps_screen = screen_region.overlaps
+
         for coord in product(
             range(x1 // block_width, x2 // block_width + 1),
             range(y1 // block_height, y2 // block_height + 1),
@@ -111,4 +117,13 @@ class SpatialMap:
             if block_placements is not None:
                 extend_placements(block_placements)
 
-        return list(placements)
+        _placements = [
+            placement
+            for placement in self._placements
+            if placement in placements and not placement.fixed
+        ]
+
+        visible_placements = self._fixed + [
+            placement for placement in _placements if overlaps_screen(placement.region)
+        ]
+        return visible_placements
diff --git a/src/textual/widget.py b/src/textual/widget.py
index 292b670ba..275320558 100644
--- a/src/textual/widget.py
+++ b/src/textual/widget.py
@@ -759,14 +759,12 @@ class Widget(DOMNode):
     def watch_scroll_x(self, new_value: float) -> None:
         if self.show_horizontal_scrollbar:
             self.horizontal_scrollbar.position = int(new_value)
-            self.horizontal_scrollbar.refresh()
-            self.refresh(layout=True)
+            self.refresh(layout=True, repaint=False)
 
     def watch_scroll_y(self, new_value: float) -> None:
         if self.show_vertical_scrollbar:
             self.vertical_scrollbar.position = int(new_value)
-            self.vertical_scrollbar.refresh()
-            self.refresh(layout=True)
+            self.refresh(layout=True, repaint=False)
 
     def validate_scroll_x(self, value: float) -> float:
         return clamp(value, 0, self.max_scroll_x)
@@ -2134,12 +2132,12 @@ class Widget(DOMNode):
             layout (bool, optional): Also layout widgets in the view. Defaults to False.
         """
 
-        if layout:
+        if layout and not self._layout_required:
             self._layout_required = True
             if isinstance(self._parent, Widget):
                 self._parent._clear_arrangement_cache()
 
-        if repaint:
+        if repaint and not self._repaint_required:
             self._set_dirty(*regions)
             self._content_width_cache = (None, 0)
             self._content_height_cache = (None, 0)