The main query (from which this was the identified 'slow' bit) uses; emp_num, trans_type, a_hrs, qty_moved, wc and CreateDate in the returned fields; job, suffix, wc, oper_num and trans_num in the JOINs and trans_class, posted in the WHERE clause.

If it would be helpful I can return the whole statement, I was trying to focus on the 'slow' bit in my initial post.