diff --git a/src/components/map/Map.js b/src/components/map/Map.js
index 2db34db..cdb7aca 100644
--- a/src/components/map/Map.js
+++ b/src/components/map/Map.js
@@ -333,7 +333,7 @@ function Map({
       active={selectedToolId === "fog"}
       toolSettings={settings.fog}
       gridSize={gridSizeNormalized}
-      transparent={allowFogDrawing && !settings.fog.preview}
+      editable={allowFogDrawing && !settings.fog.preview}
     />
   );
 
diff --git a/src/components/map/MapFog.js b/src/components/map/MapFog.js
index e76cb37..9c346d0 100644
--- a/src/components/map/MapFog.js
+++ b/src/components/map/MapFog.js
@@ -1,6 +1,12 @@
-import React, { useContext, useState, useEffect, useCallback } from "react";
+import React, {
+  useContext,
+  useState,
+  useEffect,
+  useCallback,
+  useRef,
+} from "react";
 import shortid from "shortid";
-import { Group } from "react-konva";
+import { Group, Rect } from "react-konva";
 import useImage from "use-image";
 
 import diagonalPattern from "../../images/DiagonalPattern.png";
@@ -13,6 +19,7 @@ import {
   getBrushPositionForTool,
   simplifyPoints,
   getStrokeWidth,
+  mergeShapes,
 } from "../../helpers/drawing";
 import colors from "../../helpers/colors";
 import {
@@ -21,6 +28,7 @@ import {
   Tick,
 } from "../../helpers/konva";
 import useKeyboard from "../../helpers/useKeyboard";
+import useDebounce from "../../helpers/useDebounce";
 
 function MapFog({
   map,
@@ -32,7 +40,7 @@ function MapFog({
   active,
   toolSettings,
   gridSize,
-  transparent,
+  editable,
 }) {
   const { stageScale, mapWidth, mapHeight, interactionEmitter } = useContext(
     MapInteractionContext
@@ -44,12 +52,13 @@ function MapFog({
 
   const shouldHover =
     active &&
+    editable &&
     (toolSettings.type === "toggle" || toolSettings.type === "remove");
 
   const [patternImage] = useImage(diagonalPattern);
 
   useEffect(() => {
-    if (!active) {
+    if (!active || !editable) {
       return;
     }
 
@@ -80,7 +89,6 @@ function MapFog({
           },
           strokeWidth: 0.5,
           color: toolSettings.useFogCut ? "red" : "black",
-          blend: false,
           id: shortid.generate(),
           visible: true,
         });
@@ -99,7 +107,6 @@ function MapFog({
           },
           strokeWidth: 0.5,
           color: toolSettings.useFogCut ? "red" : "black",
-          blend: false,
           id: shortid.generate(),
           visible: true,
         });
@@ -210,7 +217,6 @@ function MapFog({
               },
               strokeWidth: 0.5,
               color: toolSettings.useFogCut ? "red" : "black",
-              blend: false,
               id: shortid.generate(),
               visible: true,
             };
@@ -355,14 +361,16 @@ function MapFog({
           mapWidth,
           mapHeight
         )}
-        visible={(active && !toolSettings.preview) || shape.visible}
-        opacity={transparent ? 0.5 : 1}
+        opacity={editable ? 0.5 : 1}
         fillPatternImage={patternImage}
         fillPriority={active && !shape.visible ? "pattern" : "color"}
         holes={holes}
         // Disable collision if the fog is transparent and we're not editing it
         // This allows tokens to be moved under the fog
-        hitFunc={transparent && !active ? () => {} : undefined}
+        hitFunc={editable && !active ? () => {} : undefined}
+        shadowColor={editable ? "rgba(0, 0, 0, 0)" : "rgba(0, 0, 0, 0.33)"}
+        shadowOffset={{ x: 0, y: 5 }}
+        shadowBlur={10}
       />
     );
   }
@@ -398,9 +406,41 @@ function MapFog({
     );
   }
 
+  const [fogShapes, setFogShapes] = useState(shapes);
+  useEffect(() => {
+    function shapeVisible(shape) {
+      return (active && !toolSettings.preview) || shape.visible;
+    }
+
+    if (editable) {
+      setFogShapes(shapes.filter(shapeVisible));
+    } else {
+      setFogShapes(mergeShapes(shapes));
+    }
+  }, [shapes, editable, active, toolSettings]);
+
+  const fogGroupRef = useRef();
+  const debouncedStageScale = useDebounce(stageScale, 50);
+
+  useEffect(() => {
+    const fogGroup = fogGroupRef.current;
+
+    const canvas = fogGroup.getChildren()[0].getCanvas();
+    const pixelRatio = canvas.pixelRatio || 1;
+
+    fogGroup.cache({
+      pixelRatio: Math.min(debouncedStageScale * pixelRatio, 20),
+    });
+    fogGroup.getLayer().draw();
+  }, [fogShapes, editable, active, debouncedStageScale, mapWidth]);
+
   return (
     <Group>
-      {shapes.map(renderShape)}
+      <Group ref={fogGroupRef}>
+        {/* Render a blank shape so cache works with no fog shapes */}
+        <Rect width={1} height={1} />
+        {fogShapes.map(renderShape)}
+      </Group>
       {drawingShape && renderShape(drawingShape)}
       {drawingShape &&
         toolSettings &&
diff --git a/src/components/map/controls/EdgeSnappingToggle.js b/src/components/map/controls/EdgeSnappingToggle.js
index f04bedf..44f7a10 100644
--- a/src/components/map/controls/EdgeSnappingToggle.js
+++ b/src/components/map/controls/EdgeSnappingToggle.js
@@ -4,7 +4,11 @@ import { IconButton } from "theme-ui";
 import SnappingOnIcon from "../../../icons/SnappingOnIcon";
 import SnappingOffIcon from "../../../icons/SnappingOffIcon";
 
-function EdgeSnappingToggle({ useEdgeSnapping, onEdgeSnappingChange }) {
+function EdgeSnappingToggle({
+  useEdgeSnapping,
+  onEdgeSnappingChange,
+  disabled,
+}) {
   return (
     <IconButton
       aria-label={
@@ -18,6 +22,7 @@ function EdgeSnappingToggle({ useEdgeSnapping, onEdgeSnappingChange }) {
           : "Enable Edge Snapping (S)"
       }
       onClick={() => onEdgeSnappingChange(!useEdgeSnapping)}
+      disabled={disabled}
     >
       {useEdgeSnapping ? <SnappingOnIcon /> : <SnappingOffIcon />}
     </IconButton>
diff --git a/src/components/map/controls/FogCutToggle.js b/src/components/map/controls/FogCutToggle.js
index 34c3726..d401e59 100644
--- a/src/components/map/controls/FogCutToggle.js
+++ b/src/components/map/controls/FogCutToggle.js
@@ -4,7 +4,7 @@ import { IconButton } from "theme-ui";
 import CutOnIcon from "../../../icons/FogCutOnIcon";
 import CutOffIcon from "../../../icons/FogCutOffIcon";
 
-function FogCutToggle({ useFogCut, onFogCutChange }) {
+function FogCutToggle({ useFogCut, onFogCutChange, disabled }) {
   return (
     <IconButton
       aria-label={
@@ -12,6 +12,7 @@ function FogCutToggle({ useFogCut, onFogCutChange }) {
       }
       title={useFogCut ? "Disable Fog Cutting (C)" : "Enable Fog Cutting (C)"}
       onClick={() => onFogCutChange(!useFogCut)}
+      disabled={disabled}
     >
       {useFogCut ? <CutOnIcon /> : <CutOffIcon />}
     </IconButton>
diff --git a/src/components/map/controls/FogToolSettings.js b/src/components/map/controls/FogToolSettings.js
index 201ec13..e9b7d0f 100644
--- a/src/components/map/controls/FogToolSettings.js
+++ b/src/components/map/controls/FogToolSettings.js
@@ -80,18 +80,21 @@ function BrushToolSettings({
       title: "Fog Polygon (P)",
       isSelected: settings.type === "polygon",
       icon: <FogPolygonIcon />,
+      disabled: settings.preview,
     },
     {
       id: "rectangle",
       title: "Fog Rectangle (R)",
       isSelected: settings.type === "rectangle",
       icon: <FogRectangleIcon />,
+      disabled: settings.preview,
     },
     {
       id: "brush",
       title: "Fog Brush (B)",
       isSelected: settings.type === "brush",
       icon: <FogBrushIcon />,
+      disabled: settings.preview,
     },
   ];
 
@@ -107,6 +110,7 @@ function BrushToolSettings({
         title="Toggle Fog (T)"
         onClick={() => onSettingChange({ type: "toggle" })}
         isSelected={settings.type === "toggle"}
+        disabled={settings.preview}
       >
         <FogToggleIcon />
       </RadioIconButton>
@@ -114,6 +118,7 @@ function BrushToolSettings({
         title="Erase Fog (E)"
         onClick={() => onSettingChange({ type: "remove" })}
         isSelected={settings.type === "remove"}
+        disabled={settings.preview}
       >
         <FogRemoveIcon />
       </RadioIconButton>
@@ -121,12 +126,14 @@ function BrushToolSettings({
       <FogCutToggle
         useFogCut={settings.useFogCut}
         onFogCutChange={(useFogCut) => onSettingChange({ useFogCut })}
+        disabled={settings.preview}
       />
       <EdgeSnappingToggle
         useEdgeSnapping={settings.useEdgeSnapping}
         onEdgeSnappingChange={(useEdgeSnapping) =>
           onSettingChange({ useEdgeSnapping })
         }
+        disabled={settings.preview}
       />
       <FogPreviewToggle
         useFogPreview={settings.preview}
diff --git a/src/components/map/controls/ToolSection.js b/src/components/map/controls/ToolSection.js
index a6baeb7..25b37a4 100644
--- a/src/components/map/controls/ToolSection.js
+++ b/src/components/map/controls/ToolSection.js
@@ -36,6 +36,7 @@ function ToolSection({ collapse, tools, onToolClick }) {
         onClick={() => handleToolClick(tool)}
         key={tool.id}
         isSelected={tool.isSelected}
+        disabled={tool.disabled}
       >
         {tool.icon}
       </RadioIconButton>
@@ -90,6 +91,7 @@ function ToolSection({ collapse, tools, onToolClick }) {
         onClick={() => handleToolClick(tool)}
         key={tool.id}
         isSelected={tool.isSelected}
+        disabled={tool.disabled}
       >
         {tool.icon}
       </RadioIconButton>
diff --git a/src/helpers/drawing.js b/src/helpers/drawing.js
index 8dca66b..4e60ffa 100644
--- a/src/helpers/drawing.js
+++ b/src/helpers/drawing.js
@@ -294,3 +294,40 @@ function addPolygonIntersectionToShapes(shape, intersection, shapes) {
     };
   }
 }
+
+export function mergeShapes(shapes) {
+  if (shapes.length === 0) {
+    return shapes;
+  }
+  let geometries = [];
+  for (let shape of shapes) {
+    if (!shape.visible) {
+      continue;
+    }
+    const shapePoints = shape.data.points.map(({ x, y }) => [x, y]);
+    const shapeHoles = shape.data.holes.map((hole) =>
+      hole.map(({ x, y }) => [x, y])
+    );
+    let shapeGeom = [[shapePoints, ...shapeHoles]];
+    geometries.push(shapeGeom);
+  }
+  let union = polygonClipping.union(...geometries);
+  let merged = [];
+  for (let i = 0; i < union.length; i++) {
+    let holes = [];
+    if (union[i].length > 1) {
+      for (let j = 1; j < union[i].length; j++) {
+        holes.push(union[i][j].map(([x, y]) => ({ x, y })));
+      }
+    }
+    merged.push({
+      ...shapes[0],
+      id: `merged-${i}`,
+      data: {
+        points: union[i][0].map(([x, y]) => ({ x, y })),
+        holes,
+      },
+    });
+  }
+  return merged;
+}