diff --git a/app/api/news.py b/app/api/news.py
index 199e249..f975062 100644
--- a/app/api/news.py
+++ b/app/api/news.py
@@ -65,7 +65,8 @@ async def create_source(
 ):
     from core.url_validator import validate_feed_url
     try:
-        validate_feed_url(body.feed_url)
+        # getaddrinfo(DNS) 는 blocking — 이벤트 루프 점유 방지 위해 off-thread (R5)
+        await asyncio.to_thread(validate_feed_url, body.feed_url)
     except ValueError as e:
         raise HTTPException(status_code=422, detail=f"feed_url 검증 실패: {e}")
     source = NewsSource(**body.model_dump())
diff --git a/app/services/storage/local.py b/app/services/storage/local.py
index 1dcaec5..f3f3e94 100644
--- a/app/services/storage/local.py
+++ b/app/services/storage/local.py
@@ -2,6 +2,7 @@
 
 from __future__ import annotations
 
+import asyncio
 import os
 from collections.abc import AsyncIterator
 from pathlib import Path
@@ -42,7 +43,7 @@ class LocalBackend(StorageBackend):
                 to_read = _STREAM_CHUNK if remaining is None else min(_STREAM_CHUNK, remaining)
                 if to_read <= 0:
                     break
-                data = f.read(to_read)
+                data = await asyncio.to_thread(f.read, to_read)
                 if not data:
                     break
                 yield data
diff --git a/app/workers/file_watcher.py b/app/workers/file_watcher.py
index f1987cc..e94c0fb 100644
--- a/app/workers/file_watcher.py
+++ b/app/workers/file_watcher.py
@@ -17,6 +17,7 @@ Web/Blog ingest (devonagent 트랙, plan db-snuggly-petal.md):
   - sidecar (.json) 누락 시: skip 안 하고 ingest, web_meta.sidecar_missing=true
 """
 
+import asyncio
 import hashlib
 import json
 from pathlib import Path
@@ -246,7 +247,8 @@ async def watch_inbox():
     async with async_session() as session:
         # ─── Web/ 트랙 (devonagent) — DEVONthink Smart Rule 이 떨군 .html 만 진입 ───
         if web_root.exists():
-            for file_path in web_root.rglob("*.html"):
+            # rglob NFS 디렉토리 walk(blocking stat 다발)를 off-thread 로 수집 (R5).
+            for file_path in await asyncio.to_thread(lambda: list(web_root.rglob("*.html"))):
                 if not file_path.is_file() or should_skip(file_path):
                     continue
                 rel_path = str(file_path.relative_to(nas_root))
@@ -264,7 +266,8 @@ async def watch_inbox():
                 Path(sub).name, (None, None, None)
             )
 
-            for file_path in scan_root.rglob("*"):
+            # NFS 디렉토리 walk(blocking) off-thread 수집 (R5).
+            for file_path in await asyncio.to_thread(lambda: list(scan_root.rglob("*"))):
                 if not file_path.is_file() or should_skip(file_path):
                     continue
 
@@ -278,7 +281,11 @@ async def watch_inbox():
                     continue
 
                 rel_path = str(file_path.relative_to(nas_root))
-                fhash = file_hash(file_path)
+                # GB 파일 SHA-256 은 이벤트 루프를 점유 → 같은 루프의 모든 1분 주기 consumer
+                # + FastAPI 요청이 수십초~분 동시 정지. to_thread 오프로드. 스캔 루프가 이미
+                # 순차라 file_hash 는 한 번에 하나만 실행(직렬화) — 병렬 해싱 X = NFS 2.5GbE
+                # 대역폭·버퍼 메모리 blowup 방지 (R5).
+                fhash = await asyncio.to_thread(file_hash, file_path)
 
                 result = await session.execute(
                     select(Document).where(Document.file_path == rel_path)