Modify whatsnew entry

Author: davesque

doc/source/whatsnew/v1.4.0.rst

@@ -129,7 +129,6 @@ Other enhancements
 - :meth:`DataFrame.__pos__`, :meth:`DataFrame.__neg__` now retain ``ExtensionDtype`` dtypes (:issue:`43883`)
 - The error raised when an optional dependency can't be imported now includes the original exception, for easier investigation (:issue:`43882`)
 - Added :meth:`.ExponentialMovingWindow.sum` (:issue:`13297`)
-- :func:`guess_datetime_format` now correctly guesses the format of datetime strings with day of week and AM/PM placeholders (:issue:`43901`)
 
 .. ---------------------------------------------------------------------------
 
@@ -359,6 +358,7 @@ Performance improvements
 - Performance improvement in some :meth:`GroupBy.apply` operations (:issue:`42992`)
 - Performance improvement in :func:`read_stata` (:issue:`43059`)
 - Performance improvement in :meth:`to_datetime` with ``uint`` dtypes (:issue:`42606`)
+- Performance improvement in :meth:`to_datetime` with ``infer_datetime_format`` set to ``True`` (:issue:`43901`)
 - Performance improvement in :meth:`Series.sparse.to_coo` (:issue:`42880`)
 - Performance improvement in indexing with a :class:`MultiIndex` indexer on another :class:`MultiIndex` (:issue:43370`)
 - Performance improvement in :meth:`GroupBy.quantile` (:issue:`43469`)