diff --git a/B06_Section/B06_Section_Repository_Bulk.py b/B06_Section/B06_Section_Repository_Bulk.py
new file mode 100644
index 00000000..c2a83e27
--- /dev/null
+++ b/B06_Section/B06_Section_Repository_Bulk.py
@@ -0,0 +1,124 @@
+"""측점 설계를 **여러 행 한 번에** 쓰는 자리.
+
+왜 (2026-09-06 실측) — [저장]이 측점마다 `update_cross_section_design` ·
+`merge_cross_section_design_patch` 를 불렀고, 그 하나가 `SELECT` + `UPDATE` 두 왕복이다.
+DB 가 원격(`dsm.chemifactory.com`)이라 왕복 하나가 **약 12ms** 다. 22행이면 왕복 44번,
+곧 **670ms**. 측점이 많은 프로젝트일수록 선형으로 늘어난다.
+
+여기서는 세 문장으로 끝낸다 —
+  ① 노선의 측점 행을 **한 번에** 읽고
+  ② 파이썬에서 chainage 를 맞춰 JSON 을 합치고
+  ③ `UPDATE … SET data = CASE id …` 한 문장으로 되돌려 쓴다(없는 행은 다중 INSERT).
+
+`B06_Section_Repository` 가 685줄이라 700줄 한계에 걸려 파일을 나눴다. 한 행짜리 함수는
+그쪽에 그대로 두고, 여러 행을 쓸 때만 이쪽을 쓴다.
+"""
+
+from __future__ import annotations
+
+import json
+from typing import Any
+from uuid import UUID
+
+import aiomysql
+
+# 측점을 같은 자리로 볼 허용 오차(m) — 한 행짜리 함수와 같은 값을 쓴다.
+_CHAINAGE_TOLERANCE_M = 0.01
+
+
+async def merge_cross_section_designs(
+    connection: aiomysql.Connection,
+    *,
+    route_id: int,
+    entries: list[tuple[float, dict[str, Any]]],
+    replace: bool,
+    project_id: UUID | None = None,
+) -> int:
+    """측점 여러 곳의 `data.design` 을 한 번에 쓴다. 실제로 바뀐 행 수를 돌려준다.
+
+    `replace=True` 면 design 을 통째로 갈아 끼우고(`update_cross_section_design` 과 같은 뜻),
+    `False` 면 키만 얹는다(`merge_cross_section_design_patch` 와 같은 뜻).
+
+    행이 없는 측점은 `project_id` 가 오면 새로 만든다 — 구조물(비정규) 측점은 B05 확정이
+    파일만 쓰고 DB 행을 안 만들기 때문이다(한 행짜리 함수와 같은 규칙).
+    """
+    if not entries:
+        return 0
+
+    async with connection.cursor() as cursor:
+        await cursor.execute(
+            "SELECT id, chainage_m, data FROM cross_sections WHERE route_id = %s ORDER BY id",
+            (route_id,),
+        )
+        rows = await cursor.fetchall()
+
+    existing: dict[int, dict[str, Any]] = {}
+    for row_id, _chainage, raw in rows:
+        data = json.loads(raw) if isinstance(raw, str) else raw
+        existing[int(row_id)] = data if isinstance(data, dict) else {}
+    # 같은 측점이 여러 행이면 뒤에 온 것(=큰 id)을 쓴다 — 한 행짜리 함수의 `ORDER BY id DESC`.
+    ordered = [(float(chainage), int(row_id)) for row_id, chainage, _ in rows]
+
+    def find(chainage_m: float) -> int | None:
+        best: int | None = None
+        for value, row_id in ordered:
+            if abs(value - chainage_m) < _CHAINAGE_TOLERANCE_M and (best is None or row_id > best):
+                best = row_id
+        return best
+
+    updates: list[tuple[int, str]] = []
+    inserts: list[tuple[str, int, float, str]] = []
+    for chainage_m, payload in entries:
+        if not payload and not replace:
+            continue
+        row_id = find(chainage_m)
+        if row_id is None:
+            if project_id is None:
+                continue
+            inserts.append(
+                (
+                    str(project_id),
+                    route_id,
+                    chainage_m,
+                    json.dumps({"design": payload}, ensure_ascii=False),
+                )
+            )
+            continue
+        data = dict(existing[row_id])
+        if replace:
+            data["design"] = payload
+        else:
+            design = data.get("design")
+            design = dict(design) if isinstance(design, dict) else {}
+            design.update(payload)
+            data["design"] = design
+        updates.append((row_id, json.dumps(data, ensure_ascii=False)))
+
+    written = 0
+    async with connection.cursor() as cursor:
+        if updates:
+            # 한 문장 — `CASE id WHEN … THEN …` 이라 왕복이 한 번이다.
+            cases = " ".join("WHEN %s THEN %s" for _ in updates)
+            params: list[Any] = []
+            for row_id, blob in updates:
+                params.extend((row_id, blob))
+            params.extend(row_id for row_id, _ in updates)
+            placeholders = ", ".join("%s" for _ in updates)
+            await cursor.execute(
+                f"UPDATE cross_sections SET data = CASE id {cases} END "
+                f"WHERE id IN ({placeholders})",
+                params,
+            )
+            written += len(updates)
+        if inserts:
+            values = ", ".join("(%s, %s, %s, %s, 'DRAFT')" for _ in inserts)
+            flat: list[Any] = []
+            for item in inserts:
+                flat.extend(item)
+            await cursor.execute(
+                "INSERT INTO cross_sections (project_id, route_id, chainage_m, data, status) "
+                f"VALUES {values}",
+                flat,
+            )
+            written += len(inserts)
+    return written
diff --git a/B06_Section/B06_Section_Router_Confirm.py b/B06_Section/B06_Section_Router_Confirm.py
index c5f8c20f..c88978d8 100644
--- a/B06_Section/B06_Section_Router_Confirm.py
+++ b/B06_Section/B06_Section_Router_Confirm.py
@@ -28,11 +28,10 @@ from B06_Section.B06_Section_Repository import (
     get_cross_section_designs,
     get_cross_sections_missing_design_chainages,
     get_longitudinal_section,
-    merge_cross_section_design_patch,
     merge_longitudinal_section_data,
     merge_longitudinal_section_options,
-    update_cross_section_design,
 )
+from B06_Section.B06_Section_Repository_Bulk import merge_cross_section_designs
 
 # 원본은 `B06_Section_Router_Design` 이다 — `B06_Section_Router` 를 거쳐 들여오던 것을
 # 곧바로 잇는다(2026-09-06). 그 재수출이 없어지면서 서버가 뜨지 못했다.
@@ -95,14 +94,14 @@ async def _apply_section_edits(
     project_id: UUID | None = None,
 ) -> None:
     """임시 저장과 확정이 **함께 쓰는** 저장 본체. 트랜잭션은 호출한 쪽이 연다."""
-    for chainage_m, design in default_designs:
-        await update_cross_section_design(
-            connection,
-            route_id=route_id,
-            chainage_m=chainage_m,
-            design=design,
-            project_id=project_id,
-        )
+    # 행마다 쓰면 원격 DB 왕복이 행 수만큼 난다(측정: 22행 670ms) — 한 문장으로 묶는다.
+    await merge_cross_section_designs(
+        connection,
+        route_id=route_id,
+        entries=list(default_designs),
+        replace=True,
+        project_id=project_id,
+    )
     if request and request.standard_cross_section:
         await merge_longitudinal_section_options(
             connection,
@@ -116,6 +115,7 @@ async def _apply_section_edits(
         )
     # 프론트 세션 보관값(암 경계선 오프셋 등)을 측점별 design에 병합.
     if request and request.cross_patches:
+        patches: list[tuple[float, dict[str, Any]]] = []
         for patch_item in request.cross_patches:
             patch: dict[str, Any] = {}
             if patch_item.rock_boundary_offset_m is not None:
@@ -163,9 +163,11 @@ async def _apply_section_edits(
                 if value is not None:
                     patch[area_key] = value
             if patch:
-                await merge_cross_section_design_patch(
-                    connection, route_id=route_id, chainage_m=patch_item.chainage_m, patch=patch
-                )
+                patches.append((patch_item.chainage_m, patch))
+        # 측점 patch 도 한 문장으로 — 전 측점을 보내는 저장에서 왕복이 측점 수만큼 났다.
+        await merge_cross_section_designs(
+            connection, route_id=route_id, entries=patches, replace=False
+        )
 
 
 async def _recompute_stored_designs(project_id: UUID, route_id: int) -> None:
diff --git a/B06_Section/B06_Section_Server_Calc_Prebuild.py b/B06_Section/B06_Section_Server_Calc_Prebuild.py
index 4fd59c1c..306559e3 100644
--- a/B06_Section/B06_Section_Server_Calc_Prebuild.py
+++ b/B06_Section/B06_Section_Server_Calc_Prebuild.py
@@ -32,10 +32,9 @@ from uuid import UUID
 from B03_FileInput.B03_FileInput_Repository import get_project_storage_relative_path
 from B06_Section.B06_Section_Repository import (
     get_longitudinal_section,
-    merge_cross_section_design_patch,
     merge_longitudinal_section_data,
-    update_cross_section_design,
 )
+from B06_Section.B06_Section_Repository_Bulk import merge_cross_section_designs
 from common_util.common_util_node_bundle import run_bundle_json
 from common_util.common_util_storage import resolve_stored_project_path
 from config.config_db import get_db_pool
@@ -153,29 +152,26 @@ async def _recompute(project_id: UUID | str, route_id: int) -> int:
 
         await connection.begin()
         try:
-            for item in fixed:
-                await update_cross_section_design(
-                    connection,
-                    route_id=route_id,
-                    chainage_m=float(item.get("chainage_m") or 0.0),
-                    design=item["design"],
-                    project_id=project_uuid,
-                )
+            # 행마다 쓰면 원격 DB 왕복이 행 수만큼 난다(측정: 22행 670ms) — 한 문장으로 묶는다.
+            await merge_cross_section_designs(
+                connection,
+                route_id=route_id,
+                entries=[(float(item.get("chainage_m") or 0.0), item["design"]) for item in fixed],
+                replace=True,
+                project_id=project_uuid,
+            )
+            area_entries: list[tuple[float, dict[str, Any]]] = []
             for row in rows if isinstance(rows, list) else []:
                 patch: dict[str, Any] = {
                     key: float(row[key])
                     for key in _AREA_KEYS
                     if isinstance(row.get(key), (int, float))
                 }
-                if not patch:
-                    continue
-                if await merge_cross_section_design_patch(
-                    connection,
-                    route_id=route_id,
-                    chainage_m=float(row["chainage_m"]),
-                    patch=patch,
-                ):
-                    updated += 1
+                if patch:
+                    area_entries.append((float(row["chainage_m"]), patch))
+            updated = await merge_cross_section_designs(
+                connection, route_id=route_id, entries=area_entries, replace=False
+            )
             if isinstance(mass_haul, dict):
                 await merge_longitudinal_section_data(
                     connection, route_id=route_id, data_patch={"mass_haul": mass_haul}