PERF: Faster comparisons of indexes when the same

Author: topper-123

pandas/core/indexes/base.py

@@ -5379,6 +5379,13 @@ def _cmp_method(self, other, op):
         """
         Wrapper used to dispatch comparison operations.
         """
+        if self.is_(other):
+            # short-circuit when other is same as self
+            if op in (operator.eq, operator.le, operator.ge):
+                return np.ones(self.shape, dtype=bool)
+            elif op in (operator.ne, operator.lt, operator.gt):
+                return np.zeros(self.shape, dtype=bool)
+
         if isinstance(other, (np.ndarray, Index, ABCSeries, ExtensionArray)):
             if other.ndim > 0 and len(self) != len(other):
                 raise ValueError("Lengths must match to compare")