[ perf ] Replace json-> orjson in hot path (#11221)

Signed-off-by: vincentzed <207368749+vincentzed@users.noreply.github.com>

python/sglang/srt/entrypoints/context.py

@@ -5,6 +5,8 @@ import logging
 from abc import ABC, abstractmethod
 from typing import Union
 
+import orjson
+
 logger = logging.getLogger(__name__)
 
 try:
@@ -148,7 +150,7 @@ class HarmonyContext(ConversationContext):
         if isinstance(tool_session, Tool):
             return await tool_session.get_result(self)
         tool_name = last_msg.recipient.split(".")[1]
-        args = json.loads(last_msg.content[0].text)
+        args = orjson.loads(last_msg.content[0].text)
         result = await tool_session.call_tool(tool_name, args)
         result_str = result.content[0].text
         content = TextContent(text=result_str)