Are the records specified in you sort order indexed? Specifing indexed fields in your sort order produces a faster sort than unindexed fields. You can check the storage tab in field options or the storage options button in specify calculation to check this setting.
The same is true for performing a find.
If the most recent job is also the most recently create record in your table. Leaving the records unsorted, showing all records and going to the last record in the found set will find the most recent record without any sorting.