PERF: RangeIndex.format perf regression

Author: topper-123

pandas/core/indexes/range.py

@@ -1,7 +1,7 @@
 from datetime import timedelta
 import operator
 from sys import getsizeof
-from typing import Any
+from typing import Any, List
 import warnings
 
 import numpy as np
@@ -187,6 +187,11 @@ def _format_data(self, name=None):
         # we are formatting thru the attributes
         return None
 
+    def _format_with_header(self, header, na_rep="NaN") -> List[str]:
+        start_str, stop_str = str(self._range.start), str(self._range.stop)
+        max_length = max(len(start_str), len(stop_str))
+        return header + [f"{x:<{max_length}}" for x in self._range]
+
     # --------------------------------------------------------------------
     _deprecation_message = (
         "RangeIndex.{} is deprecated and will be "

pandas/tests/indexes/ranges/test_range.py

@@ -171,8 +171,14 @@ def test_cache(self):
             pass
         assert idx._cache == {}
 
+        idx.format()
+        assert idx._cache == {}
+
         df = pd.DataFrame({"a": range(10)}, index=idx)
 
+        str(df)
+        assert idx._cache == {}
+
         df.loc[50]
         assert idx._cache == {}