diff --git a/apps/web/src/widgets/map3d/hooks/useZonesLayer.ts b/apps/web/src/widgets/map3d/hooks/useZonesLayer.ts
index 6215356..ea1f29e 100644
--- a/apps/web/src/widgets/map3d/hooks/useZonesLayer.ts
+++ b/apps/web/src/widgets/map3d/hooks/useZonesLayer.ts
@@ -1,4 +1,4 @@
-import { useEffect, type MutableRefObject } from 'react';
+import { useEffect, useMemo, type MutableRefObject } from 'react';
 import maplibregl, {
   type GeoJSONSource,
   type GeoJSONSourceSpecification,
@@ -54,6 +54,12 @@ export function useZonesLayer(
 ) {
   const { zones, overlays, projection, baseMap, hoveredZoneId, mapSyncEpoch } = opts;
 
+  // globe용 간소화 데이터를 미리 캐싱 — ensure() 내 매번 재계산 방지
+  const simplifiedZones = useMemo(
+    () => (zones ? simplifyZonesForGlobe(zones) : null),
+    [zones],
+  );
+
   useEffect(() => {
     const map = mapRef.current;
     if (!map) return;
@@ -75,26 +81,32 @@ export function useZonesLayer(
     zoneLabelExpr.push(['coalesce', ['get', 'zoneName'], ['get', 'zoneLabel'], ['get', 'NAME'], '수역']);
 
     const ensure = () => {
-      if (projectionBusyRef.current) return;
+      // 소스 데이터 간소화 — projectionBusy 중에도 실행해야 함
+      // globe 전환 시 projectionBusy 가드 뒤에서만 실행하면 MapLibre가
+      // 원본(2100+ vertex) 데이터로 globe tessellation → 73,000+ vertex → 노란 막대
+      const sourceData = projection === 'globe' ? simplifiedZones : zones;
+      if (sourceData) {
+        try {
+          const existing = map.getSource(srcId) as GeoJSONSource | undefined;
+          if (existing) existing.setData(sourceData);
+        } catch { /* ignore — source may not exist yet */ }
+      }
+
       const visibility: 'visible' | 'none' = overlays.zones ? 'visible' : 'none';
-      // globe 모드에서 fill polygon은 tessellation으로 vertex 65535 초과 → 숨김
-      // (해안선 디테일 2100+ vertex가 globe에서 100,000+로 폭증하여 노란 막대 아티팩트 발생)
       const fillVisibility: 'visible' | 'none' = projection === 'globe' ? 'none' : visibility;
       guardedSetVisibility(map, fillId, fillVisibility);
       guardedSetVisibility(map, lineId, visibility);
       guardedSetVisibility(map, labelId, visibility);
 
+      if (projectionBusyRef.current) return;
       if (!zones) return;
       if (!map.isStyleLoaded()) return;
 
       try {
-        // globe: 서브샘플링된 데이터로 vertex 폭증 방지, mercator: 원본 데이터
-        const sourceData = projection === 'globe' ? simplifyZonesForGlobe(zones) : zones;
-        const existing = map.getSource(srcId) as GeoJSONSource | undefined;
-        if (existing) {
-          existing.setData(sourceData);
-        } else {
-          map.addSource(srcId, { type: 'geojson', data: sourceData } as GeoJSONSourceSpecification);
+        // 소스가 아직 없으면 생성 (setData는 위에서 이미 처리됨)
+        if (!map.getSource(srcId)) {
+          const data = projection === 'globe' ? simplifiedZones ?? zones : zones;
+          map.addSource(srcId, { type: 'geojson', data: data! } as GeoJSONSourceSpecification);
         }
 
         const style = map.getStyle();
@@ -247,5 +259,5 @@ export function useZonesLayer(
     return () => {
       stop();
     };
-  }, [zones, overlays.zones, projection, baseMap, hoveredZoneId, mapSyncEpoch, reorderGlobeFeatureLayers]);
+  }, [zones, simplifiedZones, overlays.zones, projection, baseMap, hoveredZoneId, mapSyncEpoch, reorderGlobeFeatureLayers]);
 }