PERF: _maybe_convert_value_to_local (#35070)

Author: jbrockmendel

asv_bench/benchmarks/tslibs/timestamp.py

@@ -63,9 +63,6 @@ def time_tz(self, tz, freq):
  def time_dayofweek(self, tz, freq):
  self.ts.dayofweek
 
- def time_weekday_name(self, tz, freq):
- self.ts.day_name
-
  def time_dayofyear(self, tz, freq):
  self.ts.dayofyear
 
@@ -108,6 +105,9 @@ def time_microsecond(self, tz, freq):
  def time_month_name(self, tz, freq):
  self.ts.month_name()
 
+ def time_weekday_name(self, tz, freq):
+ self.ts.day_name()
+
 
 class TimestampOps:
  params = [None, "US/Eastern", pytz.UTC, dateutil.tz.tzutc()]

pandas/_libs/tslibs/timestamps.pyx

@@ -47,6 +47,7 @@ from pandas._libs.tslibs.nattype cimport NPY_NAT, c_NaT as NaT
 from pandas._libs.tslibs.np_datetime cimport (
  check_dts_bounds, npy_datetimestruct, dt64_to_dtstruct,
  cmp_scalar,
+ pydatetime_to_dt64,
 )
 from pandas._libs.tslibs.np_datetime import OutOfBoundsDatetime
 from pandas._libs.tslibs.offsets cimport to_offset, is_tick_object, is_offset_object
@@ -376,9 +377,13 @@ cdef class _Timestamp(ABCTimestamp):
  """Convert UTC i8 value to local i8 value if tz exists"""
  cdef:
  int64_t val
- val = self.value
- if self.tz is not None and not is_utc(self.tz):
- val = tz_convert_single(self.value, UTC, self.tz)
+ tzinfo own_tz = self.tzinfo
+ npy_datetimestruct dts
+
+ if own_tz is not None and not is_utc(own_tz):
+ val = pydatetime_to_dt64(self, &dts) + self.nanosecond
+ else:
+ val = self.value
  return val
 
  cdef bint _get_start_end_field(self, str field):