diff --git a/backend/backfill_agg_trades.py b/backend/backfill_agg_trades.py
index 10bc0eb..249ddbf 100644
--- a/backend/backfill_agg_trades.py
+++ b/backend/backfill_agg_trades.py
@@ -27,7 +27,7 @@ logger = logging.getLogger("backfill")
 BINANCE_FAPI = "https://fapi.binance.com/fapi/v1"
 HEADERS = {"User-Agent": "Mozilla/5.0 ArbitrageEngine/backfill"}
 BATCH_SIZE = 1000
-SLEEP_MS = 200  # PG并发无锁，全速拉取
+SLEEP_MS = 500  # 平衡速度与CPU负载
 
 
 # ─── DB helpers ──────────────────────────────────────────────────