Performance improvement in :class:BusinessHour, repr is now 4 times faster ! Related to pandas-dev#44764

Author: Sylvain MARIE

doc/source/whatsnew/v1.5.0.rst

@@ -385,6 +385,7 @@ Performance improvements
 - Performance improvement when setting values in a pyarrow backed string array (:issue:`46400`)
 - Performance improvement in :func:`factorize` (:issue:`46109`)
 - Performance improvement in :class:`DataFrame` and :class:`Series` constructors for extension dtype scalars (:issue:`45854`)
+- Performance improvement in :class:`BusinessHour`, ``repr`` is now 4 times faster ! (related to :issue:`44764`)
 
 .. ---------------------------------------------------------------------------
 .. _whatsnew_150.bug_fixes:

pandas/_libs/tslibs/offsets.pyx

@@ -1566,8 +1566,10 @@ cdef class BusinessHour(BusinessMixin):
 
     def _repr_attrs(self) -> str:
         out = super()._repr_attrs()
+        # Use python string formatting to be faster than strftime
+        #   f'{st.strftime("%H:%M")}-{en.strftime("%H:%M")}'
         hours = ",".join(
-            f'{st.strftime("%H:%M")}-{en.strftime("%H:%M")}'
+            f'{st.hour:02d}:{st.minute:02d}-{en.hour:02d}:{en.minute:02d}'
             for st, en in zip(self.start, self.end)
         )
         attrs = [f"{self._prefix}={hours}"]