From f655f47d84e00a6bfa4dda38c6294021c9b65de6 Mon Sep 17 00:00:00 2001
From: Ryan Crabbe <rcrabbe@berkeley.edu>
Date: Wed, 28 Jan 2026 17:30:41 -0800
Subject: [PATCH 1/3] perf: skip Pydantic model construction in get_api_base
 when api_base is in dict
MIME-Version: 1.0
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Add fast path to check optional_params.get("api_base") directly before
constructing a full LiteLLM_Params Pydantic model. When api_base is present
(the common case via router), return it immediately — avoiding ~29µs of
Pydantic validation overhead per request.

Profiled: get_api_base 30.5µs/call → 1.2µs/call (-96%)
---
 .../litellm_core_utils/llm_response_utils/get_api_base.py  | 7 +++++++
 1 file changed, 7 insertions(+)

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..c633f421059 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 _api_base is not None:
+            return _api_base
+
     try:
         if isinstance(optional_params, LiteLLM_Params):
             _optional_params = optional_params

From 769d1777fca97ece5dc1a3141a4dcff1dfa8e8dd Mon Sep 17 00:00:00 2001
From: Ryan Crabbe <rcrabbe@berkeley.edu>
Date: Sat, 7 Feb 2026 09:51:51 -0800
Subject: [PATCH 2/3] fix: add isinstance(str) check to get_api_base fast path

Ensures non-string api_base values (e.g. int, list) fall through
to Pydantic validation instead of being returned directly.
---
 litellm/litellm_core_utils/llm_response_utils/get_api_base.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

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 c633f421059..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
@@ -32,7 +32,7 @@ def get_api_base(
     # without constructing a full LiteLLM_Params Pydantic model.
     if isinstance(optional_params, dict):
         _api_base = optional_params.get("api_base")
-        if _api_base is not None:
+        if isinstance(_api_base, str):
             return _api_base
 
     try:

From d337713976b33d3c9394e4f368195ec966fcf879 Mon Sep 17 00:00:00 2001
From: Ryan Crabbe <rcrabbe@berkeley.edu>
Date: Sat, 7 Feb 2026 11:01:40 -0800
Subject: [PATCH 3/3] test: add tests for isinstance guard on api_base fast
 path

---
 .../litellm_core_utils/test_get_api_base.py      | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)
 create mode 100644 tests/test_litellm/litellm_core_utils/test_get_api_base.py

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"