diff --git a/litellm/litellm_core_utils/llm_response_utils/get_api_base.py b/litellm/litellm_core_utils/llm_response_utils/get_api_base.py
index c23bbb936b9..253e975178a 100644
--- a/litellm/litellm_core_utils/llm_response_utils/get_api_base.py
+++ b/litellm/litellm_core_utils/llm_response_utils/get_api_base.py
@@ -28,6 +28,13 @@ def get_api_base(
     ```
     """
 
+    # Fast path: if api_base is already in the dict, return it directly
+    # without constructing a full LiteLLM_Params Pydantic model.
+    if isinstance(optional_params, dict):
+        _api_base = optional_params.get("api_base")
+        if isinstance(_api_base, str):
+            return _api_base
+
     try:
         if isinstance(optional_params, LiteLLM_Params):
             _optional_params = optional_params
diff --git a/tests/test_litellm/litellm_core_utils/test_get_api_base.py b/tests/test_litellm/litellm_core_utils/test_get_api_base.py
new file mode 100644
index 00000000000..19cc5b8e28b
--- /dev/null
+++ b/tests/test_litellm/litellm_core_utils/test_get_api_base.py
@@ -0,0 +1,16 @@
+from litellm.litellm_core_utils.llm_response_utils.get_api_base import get_api_base
+
+
+def test_get_api_base_rejects_non_string_api_base():
+    """When api_base is in dict but not a string, fast path should be skipped."""
+    result = get_api_base(model="gpt-3.5-turbo", optional_params={"api_base": 123})
+    assert result is None or isinstance(result, str)
+
+
+def test_get_api_base_fast_path_returns_string():
+    """When api_base is a valid string in dict, fast path should return it directly."""
+    result = get_api_base(
+        model="gpt-3.5-turbo",
+        optional_params={"api_base": "https://my-proxy.example.com"},
+    )
+    assert result == "https://my-proxy.example.com"