diff --git a/viewer/image_viewer/JFJochImage.cpp b/viewer/image_viewer/JFJochImage.cpp
index ff5752e0..c266660b 100644
--- a/viewer/image_viewer/JFJochImage.cpp
+++ b/viewer/image_viewer/JFJochImage.cpp
@@ -43,7 +43,7 @@ JFJochImage::JFJochImage(QWidget *parent) : QGraphicsView(parent) {
 }
 
 void JFJochImage::onScroll(int value) {
-    updateOverlay();
+    scheduleOverlayUpdate();
 }
 
 void JFJochImage::changeBackground(float val) {
@@ -122,7 +122,7 @@ void JFJochImage::wheelEvent(QWheelEvent *event) {
         QPointF delta = targetScenePos - updatedViewportCenter;
         translate(delta.x(), delta.y()); // Shift the view
 
-        updateOverlay();
+        scheduleOverlayUpdate();
         emitViewportChanged();
     }
 }
@@ -140,7 +140,7 @@ void JFJochImage::resizeEvent(QResizeEvent *event) {
     if (!initial_fit_done_)
         fitToViewShorterSideOnce();
 
-    updateOverlay();
+    scheduleOverlayUpdate();
 }
 
 QPointF JFJochImage::RoundPoint(const QPointF &input) {
@@ -221,7 +221,7 @@ void JFJochImage::mouseMoveEvent(QMouseEvent *event) {
             horizontalScrollBar()->setValue(horizontalScrollBar()->value() - viewDelta.x());
             verticalScrollBar()->setValue(verticalScrollBar()->value() - viewDelta.y());
 
-            updateOverlay();
+            scheduleOverlayUpdate();
             emitViewportChanged();
             break;
         }
@@ -272,7 +272,7 @@ void JFJochImage::mouseMoveEvent(QMouseEvent *event) {
             // Update hover state so overlay can draw arrows/handles accordingly
             if (h != hover_handle_) {
                 hover_handle_ = h;
-                updateOverlay();
+                scheduleOverlayUpdate();
             }
             // Set an informative cursor
             switch (h) {
@@ -837,6 +837,22 @@ void JFJochImage::resetScenePointers() {
     overlay_items_.clear();
 }
 
+void JFJochImage::scheduleOverlayUpdate() {
+    // Coalesce a burst of navigation events into one overlay rebuild. A single
+    // pan step, for instance, emits valueChanged on both scrollbars plus a
+    // direct call - 3 rebuilds for one visual change. Rebuilding tears down and
+    // recreates every spot/prediction/ROI item, so collapsing the duplicates to
+    // one rebuild on the next event-loop pass sharply cuts CPU and, over remote
+    // X forwarding, rasterised-pixel traffic.
+    if (overlay_update_scheduled_)
+        return;
+    overlay_update_scheduled_ = true;
+    QTimer::singleShot(0, this, [this]() {
+        overlay_update_scheduled_ = false;
+        updateOverlay();
+    });
+}
+
 void JFJochImage::updateOverlay() {
     if (!scene() || W * H <= 0) return;
 
diff --git a/viewer/image_viewer/JFJochImage.h b/viewer/image_viewer/JFJochImage.h
index a6955915..894ccd8b 100644
--- a/viewer/image_viewer/JFJochImage.h
+++ b/viewer/image_viewer/JFJochImage.h
@@ -17,6 +17,10 @@ class JFJochImage : public QGraphicsView {
 
     bool m_adjustForegroundWithWheel = false;
 
+    // Coalescing guard for scheduleOverlayUpdate(): collapses a burst of
+    // navigation events into a single overlay rebuild on the next event loop.
+    bool overlay_update_scheduled_ = false;
+
     // Viewport-lock support: guard prevents the emit<->apply ping-pong between
     // two linked views, and the helper broadcasts the current transform+center.
     bool m_applyingViewport = false;
@@ -104,6 +108,7 @@ protected:
     ResizeHandle hitTestROIHandle(const QPointF& scenePos, qreal tol = 3.0) const;
 
     void updateOverlay();
+    void scheduleOverlayUpdate();
     void GeneratePixmap();
     void Redraw();
     void CalcROI();