use ORJSONResponse when available to improve the efficiency of request process (#33548)

Signed-off-by: augusto.yjh <augusto.yjh@antgroup.com>

vllm/entrypoints/pooling/embed/api_router.py

 # SPDX-License-Identifier: Apache-2.0
 # SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+import importlib.util
+from functools import lru_cache
 from http import HTTPStatus
 
 from fastapi import APIRouter, Depends, Request
@@ -15,9 +17,24 @@ from vllm.entrypoints.pooling.embed.protocol import (
 )
 from vllm.entrypoints.pooling.embed.serving import OpenAIServingEmbedding
 from vllm.entrypoints.utils import load_aware_call, with_cancellation
+from vllm.logger import init_logger
 
 router = APIRouter()
 
+logger = init_logger(__name__)
+
+
+@lru_cache(maxsize=1)
+def _get_json_response_cls():
+    if importlib.util.find_spec("orjson") is not None:
+        from fastapi.responses import ORJSONResponse
+
+        return ORJSONResponse
+    logger.warning_once(
+        "To make v1/embeddings API fast, please install orjson by `pip install orjson`"
+    )
+    return JSONResponse
+
 
 def embedding(request: Request) -> OpenAIServingEmbedding | None:
     return request.app.state.openai_serving_embedding
@@ -54,7 +71,7 @@ async def create_embedding(
             content=generator.model_dump(), status_code=generator.error.code
         )
     elif isinstance(generator, EmbeddingResponse):
-        return JSONResponse(content=generator.model_dump())
+        return _get_json_response_cls()(content=generator.model_dump())
     elif isinstance(generator, EmbeddingBytesResponse):
         return StreamingResponse(
             content=generator.content,