requested doc changes

Author: realead

doc/source/whatsnew/v1.2.0.rst

@@ -376,7 +376,7 @@ Performance improvements
 - Reduced peak memory usage in :meth:`DataFrame.to_pickle` when using ``protocol=5`` in python 3.8+ (:issue:`34244`)
 - faster ``dir`` calls when many index labels, e.g. ``dir(ser)`` (:issue:`37450`)
 - Performance improvement in :class:`ExpandingGroupby` (:issue:`37064`)
-- Performance improvement in :meth:`pd.DataFrame.groupby` for ``float`` ``dtype`` (:issue:`28303`)
+- Performance improvement in :meth:`pd.DataFrame.groupby` for ``float`` ``dtype`` (:issue:`28303`), changes of the underlying hash-function can lead to changes in float based indexes sort ordering for ties (e.g. :meth:`pd.Index.value_counts`)
 
 .. ---------------------------------------------------------------------------
 

pandas/_libs/src/klib/khash_python.h

@@ -15,7 +15,7 @@
 // hash for 64 bit integers.
 // GH 13436 showed that _Py_HashDouble doesn't work well with khash
 // GH 28303 showed, that the simple xoring-version isn't good enough
-// thus murmur2-hash is used
+// See GH 36729 for evaluation of the currently used murmur2-hash version
 
 khint64_t PANDAS_INLINE asint64(double key) {
     khint64_t val;