After seeing the patch posted by eholme I did some research into MySQL queries, specifically the use of LEFT JOIN vs. INNER JOIN, and found that the use of LEFT JOIN within Order Editor was totally unnecessary.

The following changes were made for this version:
-the query eholme optimized was deleted
-all remaining instances of LEFT JOIN were replaced with INNER JOIN
-cleaned up the code for a number of queries to make them easier to read

Changed files: admin/edit_orders.php, admin/search_suggest.php, admin/includes/classes/oe_order.php

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