No need to rebuild a constant dictionary on every call. Move convert mapping to module level.

Lib/functools.py

@@ -174,9 +174,7 @@ def _lt_from_ge(self, other):
         return op_result
     return not op_result
 
-def total_ordering(cls):
-    """Class decorator that fills in missing ordering methods"""
-    convert = {
+_convert = {
     '__lt__': [('__gt__', _gt_from_lt),
                ('__le__', _le_from_lt),
                ('__ge__', _ge_from_lt)],
@@ -190,12 +188,15 @@ def total_ordering(cls):
                ('__gt__', _gt_from_ge),
                ('__lt__', _lt_from_ge)]
 }
+
+def total_ordering(cls):
+    """Class decorator that fills in missing ordering methods"""
     # Find user-defined comparisons (not those inherited from object).
-    roots = [op for op in convert if getattr(cls, op, None) is not getattr(object, op, None)]
+    roots = [op for op in _convert if getattr(cls, op, None) is not getattr(object, op, None)]
     if not roots:
         raise ValueError('must define at least one ordering operation: < > <= >=')
     root = max(roots)       # prefer __lt__ to __le__ to __gt__ to __ge__
-    for opname, opfunc in convert[root]:
+    for opname, opfunc in _convert[root]:
         if opname not in roots:
             opfunc.__name__ = opname
             setattr(cls, opname, opfunc)