diff --git a/src/mistralai/models/updateftmodelin.py b/src/mistralai/models/updateftmodelin.py
index 1bd0eaf..1ced33c 100644
--- a/src/mistralai/models/updateftmodelin.py
+++ b/src/mistralai/models/updateftmodelin.py
@@ -18,29 +18,35 @@ class UpdateFTModelIn(BaseModel):
 
     @model_serializer(mode="wrap")
     def serialize_model(self, handler):
-        optional_fields = ["name", "description"]
-        nullable_fields = ["name", "description"]
-        null_default_fields = []
+        # Convert lists to sets for O(1) membership tests
+        optional_fields = {"name", "description"}
+        nullable_fields = {"name", "description"}
+        null_default_fields = set()
 
         serialized = handler(self)
 
         m = {}
 
-        for n, f in type(self).model_fields.items():
+        # Cache intersection method and field values for performance
+        fields_set = self.__pydantic_fields_set__
+
+        # Avoid repeated lookups in loop
+        model_fields_items = type(self).model_fields.items()
+
+        for n, f in model_fields_items:
             k = f.alias or n
-            val = serialized.get(k)
-            serialized.pop(k, None)
+            # Use get and pop only once
+            val = serialized.pop(k, None)
 
             optional_nullable = k in optional_fields and k in nullable_fields
-            is_set = (
-                self.__pydantic_fields_set__.intersection({n})
-                or k in null_default_fields
-            )  # pylint: disable=no-member
+            # Use set intersection directly on k
+            is_set = n in fields_set or k in null_default_fields  # pylint: disable=no-member
 
+            # Reduce number of comparisons and branches
             if val is not None and val != UNSET_SENTINEL:
                 m[k] = val
             elif val != UNSET_SENTINEL and (
-                not k in optional_fields or (optional_nullable and is_set)
+                k not in optional_fields or (optional_nullable and is_set)
             ):
                 m[k] = val