Optimize _get_record

Before:

    _get_record() for 131072 addresses 0:00:19.744702
    _get_record() for 131072 addresses 0:00:19.088162
    _get_record() for 131072 addresses 0:00:19.362637
    _get_record() for 131072 addresses 0:00:19.874917

After:

    _get_record() for 131072 addresses 0:00:18.143153
    _get_record() for 131072 addresses 0:00:18.247334
    _get_record() for 131072 addresses 0:00:18.326092
    _get_record() for 131072 addresses 0:00:17.750563