perf: optimize system concurrency, I/O stability and fix WebSocket disconnects

backend/services/storage.py

@@ -7,6 +7,7 @@ Handles reading/writing dashboard JSON files and portfolio state
 import json
 import logging
 import os
+import time
 from datetime import datetime
 from pathlib import Path
 from typing import Any, Dict, List, Optional
@@ -950,11 +951,14 @@ class StorageService:
 
     def save_server_state(self, state: Dict[str, Any]):
         """
-        Save server state to file
-
-        Args:
-            state: Server state dictionary
+        Save server state to file with rate-limiting to avoid I/O storms.
         """
+        now = time.time()
+        # Ensure at least 2 seconds between physical disk writes
+        if hasattr(self, "_last_save_time") and (now - self._last_save_time) < 2.0:
+            return
+        self._last_save_time = now
+
         state_to_save = {
             **state,
             "last_saved": datetime.now().isoformat(),
@@ -970,14 +974,17 @@ class StorageService:
         if "trades" in state_to_save:
             state_to_save["trades"] = state_to_save["trades"][:100]
 
-        with open(self.server_state_file, "w", encoding="utf-8") as f:
-            json.dump(
-                state_to_save,
-                f,
-                ensure_ascii=False,
-                indent=2,
-                default=str,
-            )
+        try:
+            with open(self.server_state_file, "w", encoding="utf-8") as f:
+                # Removed indent=2 to minimize file size and serialization overhead
+                json.dump(
+                    state_to_save,
+                    f,
+                    ensure_ascii=False,
+                    default=str,
+                )
+        except Exception as e:
+            logger.error(f"Failed to save server state: {e}")
 
         logger.debug(f"Server state saved to: {self.server_state_file}")