⚡️ Speed up function merge_setting by 61%

src/requests/sessions.py

@@ -75,15 +75,13 @@ def merge_setting(request_setting, session_setting, dict_class=OrderedDict):
         isinstance(session_setting, Mapping) and isinstance(request_setting, Mapping)
     ):
         return request_setting
-
-    merged_setting = dict_class(to_key_val_list(session_setting))
-    merged_setting.update(to_key_val_list(request_setting))
-
-    # Remove keys that are set to None. Extract keys first to avoid altering
-    # the dictionary during iteration.
-    none_keys = [k for (k, v) in merged_setting.items() if v is None]
-    for key in none_keys:
-        del merged_setting[key]
+
+    merged_setting = dict_class(session_setting)
+    for key, value in request_setting.items():
+        if value is None:
+            merged_setting.pop(key, None)
+        else:
+            merged_setting[key] = value
 
     return merged_setting
 

src/requests/utils.py

@@ -369,7 +369,7 @@ def to_key_val_list(value):
         raise ValueError("cannot encode objects that are not 2-tuples")
 
     if isinstance(value, Mapping):
-        value = value.items()
+        return list(value.items())
 
     return list(value)