Speeding up Python date conversion function currently using list comprehension and datetime
You should try Numpy's datetime and timedelta support:

def days2dt(days_since_epoch):
    microseconds = np.around(np.asarray(days_since_epoch) * (24*60*60*10**6))
    return np.datetime64('1980-01-06') + microseconds.astype('timedelta64[us]')


I suggest you read the units section of the docs to make sure this is safe (both resolution and min/max dates), but it should be fine.

Note that 90% of the time taken for days2dt is converting the input list to a numpy.array; if you pass in a numpy.array it goes much faster. Nevertheless, this is significantly faster than the list comprehension already.