PERF: Using _Period for optimization (#32973)

Author: ShaharNaveh

pandas/_libs/index.pyx

@@ -479,7 +479,6 @@ cdef class PeriodEngine(Int64Engine):
  return scalar.value
  if isinstance(scalar, Period):
  # NB: we assume that we have the correct freq here.
- # TODO: potential optimize by checking for _Period?
  return scalar.ordinal
  raise TypeError(scalar)