perf: optimize polling, stats cache, and frontend chunk splitting

db/admin.py

@@ -190,41 +190,40 @@ def get_system_stats() -> dict:
     with db_pool.get_db() as conn:
         cursor = conn.cursor()
 
-        total_users = _count_scalar(cursor, "SELECT COUNT(*) as count FROM users")
-        approved_users = _count_scalar(cursor, "SELECT COUNT(*) as count FROM users WHERE status = 'approved'")
-        new_users_today = _count_scalar(
-            cursor,
+        cursor.execute(
             """
-            SELECT COUNT(*) as count
+            SELECT
+              COUNT(*) AS total_users,
+              SUM(CASE WHEN status = 'approved' THEN 1 ELSE 0 END) AS approved_users,
+              SUM(CASE WHEN date(created_at) = date('now', 'localtime') THEN 1 ELSE 0 END) AS new_users_today,
+              SUM(CASE WHEN datetime(created_at) >= datetime('now', 'localtime', '-7 days') THEN 1 ELSE 0 END) AS new_users_7d,
+              SUM(
+                CASE
+                  WHEN vip_expire_time IS NOT NULL
+                   AND datetime(vip_expire_time) > datetime('now', 'localtime')
+                  THEN 1 ELSE 0
+                END
+              ) AS vip_users
             FROM users
-            WHERE date(created_at) = date('now', 'localtime')
-            """,
-        )
-        new_users_7d = _count_scalar(
-            cursor,
             """
-            SELECT COUNT(*) as count
-            FROM users
-            WHERE datetime(created_at) >= datetime('now', 'localtime', '-7 days')
-            """,
         )
+        user_stats = cursor.fetchone() or {}
+
+        def _to_int(key: str) -> int:
+            try:
+                return int(user_stats[key] or 0)
+            except Exception:
+                return 0
+
         total_accounts = _count_scalar(cursor, "SELECT COUNT(*) as count FROM accounts")
-        vip_users = _count_scalar(
-            cursor,
-            """
-            SELECT COUNT(*) as count FROM users
-            WHERE vip_expire_time IS NOT NULL
-            AND datetime(vip_expire_time) > datetime('now', 'localtime')
-            """,
-        )
 
         return {
-            "total_users": total_users,
-            "approved_users": approved_users,
-            "new_users_today": new_users_today,
-            "new_users_7d": new_users_7d,
+            "total_users": _to_int("total_users"),
+            "approved_users": _to_int("approved_users"),
+            "new_users_today": _to_int("new_users_today"),
+            "new_users_7d": _to_int("new_users_7d"),
             "total_accounts": total_accounts,
-            "vip_users": vip_users,
+            "vip_users": _to_int("vip_users"),
         }