diff --git a/apps/web/src/comments.ts b/apps/web/src/comments.ts
index 059e0144a..181621306 100644
--- a/apps/web/src/comments.ts
+++ b/apps/web/src/comments.ts
@@ -124,6 +124,35 @@ export function commentVisibleOnDeckSlide(
   return comment.slideIndex === activeSlideIndex;
 }
 
+export function commentSnapshotOverlayEqual(
+  a: PreviewCommentSnapshot,
+  b: PreviewCommentSnapshot,
+): boolean {
+  const positionA = normalizePosition(a.position);
+  const positionB = normalizePosition(b.position);
+  return (
+    a.elementId === b.elementId
+    && a.filePath === b.filePath
+    && positionA.x === positionB.x
+    && positionA.y === positionB.y
+    && positionA.width === positionB.width
+    && positionA.height === positionB.height
+    && (a.slideIndex ?? -1) === (b.slideIndex ?? -1)
+  );
+}
+
+export function liveCommentTargetMapsEqual(
+  current: Map<string, PreviewCommentSnapshot>,
+  next: Map<string, PreviewCommentSnapshot>,
+): boolean {
+  if (current.size !== next.size) return false;
+  for (const [elementId, snapshot] of current) {
+    const candidate = next.get(elementId);
+    if (!candidate || !commentSnapshotOverlayEqual(snapshot, candidate)) return false;
+  }
+  return true;
+}
+
 export function overlayBoundsFromSnapshot(
   snapshot: PreviewCommentSnapshot,
   scale: number,
diff --git a/apps/web/src/components/FileViewer.tsx b/apps/web/src/components/FileViewer.tsx
index d9eac82ab..73a8580d1 100644
--- a/apps/web/src/components/FileViewer.tsx
+++ b/apps/web/src/components/FileViewer.tsx
@@ -93,10 +93,12 @@ import { Toast } from './Toast';
 import { PreviewDrawOverlay } from './PreviewDrawOverlay';
 import {
   buildBoardCommentAttachments,
+  commentSnapshotOverlayEqual,
   commentTargetDisplayName,
   commentVisibleOnDeckSlide,
   commentsToAttachments,
   isValidCommentOverlayPosition,
+  liveCommentTargetMapsEqual,
   liveSnapshotForComment,
   overlayBoundsFromSnapshot,
   selectionKindLabel,
@@ -4972,7 +4974,9 @@ const [manualEditTargets, setManualEditTargets] = useState<ManualEditTarget[]>([
           ...(typeof item?.slideIndex === 'number' ? { slideIndex: item.slideIndex } : {}),
         });
       });
-      setLiveCommentTargets(next);
+      setLiveCommentTargets((current) => (
+        liveCommentTargetMapsEqual(current, next) ? current : next
+      ));
     }
     window.addEventListener('message', onMessage);
     return () => window.removeEventListener('message', onMessage);
@@ -5096,32 +5100,42 @@ const [manualEditTargets, setManualEditTargets] = useState<ManualEditTarget[]>([
           if (!snapshot.elementId || !isValidCommentOverlayPosition(snapshot.position)) return;
           next.set(snapshot.elementId, snapshot);
         });
-        setLiveCommentTargets(next);
+        setLiveCommentTargets((current) => (
+          liveCommentTargetMapsEqual(current, next) ? current : next
+        ));
         setActiveCommentTarget((current) => {
           if (!current) return null;
           if (current.selectionKind === 'pod') return current;
           const updated = next.get(current.elementId);
-          if (updated && isValidCommentOverlayPosition(updated.position)) return updated;
-          return null;
+          if (!updated || !isValidCommentOverlayPosition(updated.position)) return null;
+          return commentSnapshotOverlayEqual(current, updated) ? current : updated;
         });
         setHoveredCommentTarget((current) => {
           if (!current) return null;
           if (current.selectionKind === 'pod') return current;
           const updated = next.get(current.elementId);
-          if (updated && isValidCommentOverlayPosition(updated.position)) return updated;
-          return null;
+          if (!updated || !isValidCommentOverlayPosition(updated.position)) return null;
+          return commentSnapshotOverlayEqual(current, updated) ? current : updated;
         });
         return;
       }
       if (data.type === 'od:comment-active-target-update') {
         const snapshot = snapshotFromData(data);
         if (!snapshot.elementId || !isValidCommentOverlayPosition(snapshot.position)) return;
-        setLiveCommentTargets((current) => new Map(current).set(snapshot.elementId, snapshot));
+        setLiveCommentTargets((current) => {
+          const existing = current.get(snapshot.elementId);
+          if (existing && commentSnapshotOverlayEqual(existing, snapshot)) return current;
+          return new Map(current).set(snapshot.elementId, snapshot);
+        });
         setActiveCommentTarget((current) => (
-          current && current.elementId === snapshot.elementId ? snapshot : current
+          current && current.elementId === snapshot.elementId && !commentSnapshotOverlayEqual(current, snapshot)
+            ? snapshot
+            : current
         ));
         setHoveredCommentTarget((current) => (
-          current && current.elementId === snapshot.elementId ? snapshot : current
+          current && current.elementId === snapshot.elementId && !commentSnapshotOverlayEqual(current, snapshot)
+            ? snapshot
+            : current
         ));
         return;
       }
@@ -5132,8 +5146,14 @@ const [manualEditTargets, setManualEditTargets] = useState<ManualEditTarget[]>([
       if (data.type === 'od:comment-hover') {
         const snapshot = snapshotFromData(data);
         if (!snapshot.elementId || !isValidCommentOverlayPosition(snapshot.position)) return;
-        setHoveredCommentTarget(snapshot);
-        setLiveCommentTargets((current) => new Map(current).set(snapshot.elementId, snapshot));
+        setHoveredCommentTarget((current) => (
+          current && commentSnapshotOverlayEqual(current, snapshot) ? current : snapshot
+        ));
+        setLiveCommentTargets((current) => {
+          const existing = current.get(snapshot.elementId);
+          if (existing && commentSnapshotOverlayEqual(existing, snapshot)) return current;
+          return new Map(current).set(snapshot.elementId, snapshot);
+        });
         return;
       }
       if (data.type === 'od:comment-target') {
diff --git a/apps/web/src/runtime/srcdoc.ts b/apps/web/src/runtime/srcdoc.ts
index 9c32fa3b9..7d40ee0e6 100644
--- a/apps/web/src/runtime/srcdoc.ts
+++ b/apps/web/src/runtime/srcdoc.ts
@@ -1510,7 +1510,7 @@ function meaningfulDomFallbackTarget(el) {
     schedulePostPreviewScroll();
   }, true);
   var mo = new MutationObserver(schedulePostTargets);
-  mo.observe(document.documentElement, { subtree: true, childList: true, attributes: true, characterData: true });
+  mo.observe(document.documentElement, { subtree: true, childList: true, attributes: true });
   // Reflect the host-requested initial modes on the documentElement so
   // the cursor/hover styles match what the bridge picks up on click.
   if (commentEnabled) document.documentElement.toggleAttribute('data-od-comment-mode', true);
@@ -1897,6 +1897,7 @@ function injectDeckBridge(doc: string, initialSlideIndex = 0): string {
     for (var k = 0; k < n; k++) dispatchKey(key);
     setTimeout(report, 320);
   }
+  var lastCommentTargetSlideIndex = -1;
   function report(){
     try {
       var list = slides();
@@ -1918,9 +1919,12 @@ function injectDeckBridge(doc: string, initialSlideIndex = 0): string {
         if (el.querySelector('span,.bar')) return;
         el.style.width=progressWidth;
       });
-      try {
-        if (typeof window.__odScheduleCommentTargets === 'function') window.__odScheduleCommentTargets();
-      } catch (_) {}
+      if (i !== lastCommentTargetSlideIndex) {
+        lastCommentTargetSlideIndex = i;
+        try {
+          if (typeof window.__odScheduleCommentTargets === 'function') window.__odScheduleCommentTargets();
+        } catch (_) {}
+      }
     } catch (e) {}
   }
   window.__odDeckSlideState = function(){
diff --git a/apps/web/tests/comments.test.ts b/apps/web/tests/comments.test.ts
index 088b8c83f..26f839f70 100644
--- a/apps/web/tests/comments.test.ts
+++ b/apps/web/tests/comments.test.ts
@@ -5,6 +5,7 @@ import {
   commentVisibleOnDeckSlide,
   commentsToAttachments,
   historyWithCommentAttachmentContext,
+  liveCommentTargetMapsEqual,
   liveSnapshotForComment,
   mergeAttachedComments,
   messageContentWithCommentAttachments,
@@ -265,6 +266,23 @@ describe('preview comment attachment helpers', () => {
     expect(commentVisibleOnDeckSlide({}, 1)).toBe(true);
   });
 
+  it('treats live comment target maps with identical overlay bounds as equal', () => {
+    const base: PreviewCommentSnapshot = {
+      filePath: 'index.html',
+      elementId: 'hero-title',
+      selector: '[data-od-id="hero-title"]',
+      label: 'h1.hero-title',
+      text: 'Hello',
+      htmlHint: '',
+      position: { x: 12, y: 24, width: 120, height: 32 },
+    };
+    const current = new Map([['hero-title', base]]);
+    const next = new Map([['hero-title', { ...base, text: 'Hello world' }]]);
+    expect(liveCommentTargetMapsEqual(current, next)).toBe(true);
+    next.set('hero-title', { ...base, position: { x: 13, y: 24, width: 120, height: 32 } });
+    expect(liveCommentTargetMapsEqual(current, next)).toBe(false);
+  });
+
   it('serializes selected comments into API-mode prompt context without visible input', () => {
     const attachments = commentsToAttachments([
       comment({